I am of the school that believes that the more space that you have, the more unnecessary stuff you will take with you.

As for seat bags, I've seen some that wobble like crazy. I could never ride with those. Luckily, I got a Rogue Panda Picketpost (https://rackadvisor.org/) and it is solid on my bike.

My wife and I did a variation of the North portion of the Tour Divide earlier this month and at one point I considered going with a lightweight rack. But the more I thought about at it, the more convinced I became that it likely would be a failure point due to the stresses involved with day in and out washboard, ruts, roots, rocks, etc...

This.
What everyone else said, plus -
If you're going to use rear panniers, then the bike will be horribly unbalanced. Been there, done that.
They don't work off-road. It concentrates all of the weight over the rear of the bike and screws up the handling. They seem more suited to smooth surfaces or low-speed use on rougher roads.
Frame bags etc are more durable when you're getting rattled regularly and lighter (or better luggage vs content ratio).

Usually I put my shoes under my pad, under my head, toes pointed ‘downhill’. It’s like a little ramp. Phone can go in one shoe, which is handy for an alarm clock. My bivy setup typically requires that I wear my layers when I sleep so I can’t do the clothes-in-a-stuff-sack method.

If I’m feeling luxurious and have panniers, I have a Nemo Fillo Luxury pillow, which is an outstanding bit of kit, but too big for bikepacking bags.

I also have tried all sorts of "arrangements" of gear to sleep on, including boots/shoes. We - wife and me - even tried to use a regular pillow and finally evolved just right to buy something portable. After all we were amateurs, what to say...
Take a look at the Exped air pillow (http://www.exped.com/usa/en/air-pillow-m) - I really like mine. They pack up small, you can easily control the firmness and they even come in a few different sizes should you want something close in size to a real pillow. I find that the material doesn't feel that comfortable so use a buff as a pillowcase of sorts and it works a treat.

I use a Eastern Mountain Sports "Boreal" 20°F synthetic bag. It was recently an Editor's pick in an outdoors magazine, and I can see why: it is very, very warm, it packs down well, it's lightweight and cheap. I would think the less-warm versions of this bag are good, too.
I've used it touring and backpacking in the past 4 months. The only issue I've had with it is the zipper can get snagged when hastily zipped, but the lightweight material is easy to un-snag.

For lightest options I have Kong blinder 1 led for front and back. They are 15g each, multi-mode, rechargeable. you can't really get much smaller and lighter than that.
But i am just going to say they are "better than nothing", they are (barely) good enough for night when some light is better than none - I can hardly call them useful for daytime running light.
Though I like them because they are light and small. Considering that I don't do much solo night ride so that's how i justified the minimal light output.

Also I had good experience with Lezyne. You will need at least the 900 lumen model to "see" but for being seen the smaller ones are fine.