Two dry bags directly under the seat.

The one sided connection with rear wheel on the WeeHoo eliminates mountain a front rack on that wheel.
So do an Old Man Mountain rack on the mountain bikes front wheel.
Maybe fabricate a single bag of the back of the seat (duffel bag type construction).
You might be able to mount an extra large seat bag to your seat/seatpost.

Just a thought...  I have done this with my cross top brakes for a completely different reason (to have a place to mount a light and computer).  I have one hose clamp around the stem and two hose clamps around the first clamp and around a piece of handlebar to give me another bar parallel with the handlebar.  Mine is on top but it could be done under the stem and might provide a lower place to mount a bag.  I can't do this due to the brake line that runs in front of the head tube on my LHT but it might be useful to you.
I have also seen people mount a second stem under their current stem but that would require enough fork tubing to hold two stems.

To take RiderX approach but maybe even simpler would be to use something like this...  http://www.homedepot.com/p/Everbilt-1-2-in-x-36-in-Aluminum-Flat-Bar-800207/204604761
In the States, all our major home/hardware stores carry something very similar.

Don't know if this will help or not but when I made my seat bag the most useful strap on it was one I connected to the roll top closer of the bag.  It went from the roll top closer on one side around the seatpost and back to the other side of the roll top closer.  I had intended to secure this strap to a daisy chain on the bag but found putting around the seatpost next to the clamp was the most secure spot.  I never felt the bag sway.

Those are pretty nifty.  Are they "saddlebagged" over the top tube and velcro-ed to the down tube?  I've only seen the chalk bag looking ones.
Are you looking to use the gas tank as extra storage or just easy to access storage?  It seems you have your gas tank covered with your feedbags.  But I'm a total newbe on this topic...

What is the diameter of the bags?
I know this is not the correct forum for this answer but making a stuff sack is probably the absolutely easiest thing to make.  Adding a roll top closure is pretty simple as well.  Need them to be waterproof, add a garbage back inside them.  If the Salsa bags are 32 dollars/bag, you could make a crap ton of bags for 64 dollars of materials.  And get the correct size.
Heck I'll throw it out there, for 40 dollars I will make a pair of bags made out of 8 oz pack cloth or 5 oz oxford.  Funky strap included.

What do people put in these bags.  I can figure out the sleeping bag goes on the handlebar, sleeping pad and clothes in the seat bag, shelter on the bike iteself and food/water/cooking in the backpack.  So what goes on the fork?  I would love to make two, but have no clue what to stick in them.

This could go in either this forum or the DIY but I'm hoping to get people who might not DIY...
Blackburn makes their handlebar roll sit higher on the handlebar where most designs sit under the handlebar.  https://www.blackburndesign.com/bags/outpost-bag-collection/outpost-handlebar-roll-dry-bag.html
Thanks to some aero extensions from the 1990's that fit my handlebar next to the stem, I can jack the roll up higher too.  Can anyone think of a reason why higher would be worse?  With the extra attachment points, I can see the higher would actually be more secure and I could more readily use a pocket.  It would have less tire spray too.  The center of gravity would be higher though.
Any thoughts?  The harness is going to be DIY BTW.

I'm going to make myself a backpack specifically for XC skiing/hiking (my camelback is the perfect size for summer, so this one is for the winter).  The only way I have found to prevent a drinking hose from freezing up is to lift it above my head and empty if of all water.  What to people think if the insulated hose cozies.  Would a black fleece and nylon insulation do anything?
Thanks,
Unrelated to my question is my other winter idea is putting foam backing only on the side and let the bladder sit close to my back.

Hey all,
I tried to make a battery powered (aka powered by AA type batteries) charger to charge my cell phone and it failed miserably.  I can see most chargers on the market get powered by internal batteries that can not get changed out.  I also read the reviews of a couple of the chargers on Amazon and they have the same problems as my home made one (they charge the phone battery to about 17 percent and nothing more and might actually remove power from my phone).
So can someone recommend a charger or tell me what you guys do?
Thanks,

more pics

So here is a pic of the finished product.  No pretty but I do believe it will be completely functional

Do a search for bug bivy.  Mine is a Walrus, which means its really old.  Many have two small poles that go over your head and can be set up with out any tent overhead so you can use them under the stars.  Some have a string that attaches them to a high point (your tent, a tree, a shelter beam).  Same with floors, some have them, some don't.  If you are willing to sew, it would be an easy thing to do.
DEET... Have fun convincing the bugs to care about that.

I'll post a small update.  If this works, I'll post pictures in its own post.  So far I have made the back half of it and I really do believe its going to work AND be reproducible.  I was originally going to wrap the rear frame all the way around the extra wheel but discovered it was quite sturdy and cut the rear frame in half so it looks more like a commercial Extra-Wheel.  I bought a quick release skewer from here (http://www.mayacycle.com/) instead of BOB and now need to complete the front half.  After that... It will be done.  I'll have to do some testing but assuming it tracks and doesn't fall apart, the testing should be short.

If I could weld, then absolutely and old fork would be a good starting place.  The "frame" is going to wrap around the wheel so the drop outs aren't going to have horrible stresses on them.  Hopefully I'm not making an anchor but I don't think the weight will be that bad.

So I did do something to the trail a bike that I had and concluded that is was big ugly and heavy.  I have seen the Extrawheel before and that is what I would actually have if I could justify the cost.  So I have decided to scratch the ideas with the trail a bike and attempt to make an Extrawheel from scratch.  I do believe that I can make it work by using mostly plywood.  I spent this afternoon turning a fry pan into drop outs.  Is anyone interested in me posting updates?  Before anyone points out that this is very impractical, I know that it is.  Its mostly a project to keep my mind happy and to see just what I can do (and use it when its done for weekend trips).

I guess it depends on how many days you are going to be out.  As a reference, when I hiked the AT in 2002, alcohol stoves ruled because they were easy to refuel and tiny compared to white gas.  These days it seems canister stoves rule because trail towns figure out that people want to buy canister fuel and resupply is no longer an issue.  Canisters are hotter and comparable in size when 4-7 days are considered.
If you are only going to be out 1-3 days, then alcohol is smaller.  Trangia's allow you to store alcohol in them so for over nighter you don't even need to bring a fuel bottle.
As far as soot, what dh024 said.  Denatured alcohol produces soot but not much..  Never been an issue to me personally.

Just a thought, but do you need three bags?  Can you put your clothes and sleeping bag in the same stuff sack.  Can you make a waterproof bag to to put your tent inside and then put that in your clothes/sleeping bag stuff sack?  It would seem that one bag would carry better than three.

http://www.michaels.com/creatology-foam-sheet-12x18/M10597609.html
I made a very small top tube bag with this stuff.  I also just sewed it into the fabric.