Here's my solution:
Step 1: chop up an old pair of cycling shoes.
Step 2: cut out the front portion of the sole.
Step 3: Shave down the non-studded tread on a pair of Stabilicers. Shave down the tread on the spd sole so that the screws on the stabilicers will still contact the ground.
Step 4: Double check measurements and alignment to be sure it clears your crank arm, and bolt the spd sole to the bottom of the Stabilicers.
Step 5: Buy some $50 Cabella's snow runners in the correct size, or any other warm boot of your choosing, and strap em in.
What's that? It's -80F, you've stuffed your tires with grass and want to go ride in your spds? No problem, your pac boots will work in these as well.
Add a gaiter as necessary for post-holing.
Pros:
-Stiff
-Warm
-Excellent grip on ice
-The stabilicers do not move around on my boots at all.
-Long hike-a-bike? Remove the Stabilicers(takes 5 seconds) and march along in your comfy hiking boot. Or leave em on it there's a chance of encountering ice.
-Need to walk around inside on a possibly wet floor? No problem, remove the stabilicers and you wont have to worry about chewing up the floor with the screws in the bottom of your boot.
-Wanna ride in hiking boots in the summer, with spds? No problem again.
-Size 13 feet? No problem. I ordered the Snow runners in size 14 as recommended by Cabela's for use with thick socks. I used size XL Stabilicers and they're almost a perfect match for the bottom of the Snow Runners in 14. Stabilicers come in XXL too I believe.
Cons:
-You'll need to raise your saddle and bars an inch or so, since the cleat is much further away from your foot.
I'll probably use some bigger washers under the bolt heads, just to be sure they don't rip out. If I had more time and money, I would probably do a layup of carbon fiber on the top of the Stabilicers, with a cut out for the cleat. It would be stiffer, and look better.
Even if you bought everything new(using a really cheap pair of cycling shoes), total cost would be around $150, and you would be getting a nice pair of winter hiking boots out of the deal.