Looks like I'd better update my packing situation, since at least one ALCer saw the previous photo and thought I'd made everything fit by that point. I hadn't. But now I have. Stuff is in two layers. Here's the bottom layer:

1. Three days of cycling clothes, each in a separate bag, and a bag with an extra set of underwear and socks. With the one set of cycling clothes I wear on Day 1, that's four sets of clothes. I plan to do laundry in Paso Robles, where I have a hotel room.
2. Tissues.
3. Air mattress, continuing underneath #4.
4. Camp pillow.
5. Lantern for tent.
6. 20-degree mummy sack, heavily compressed.
7. Food and supplies, such as gels, cough drops, and butt cream.
8. Camp bottle. (We'll probably get a new one tomorrow.)
9. Fleece workout pants, heavy fleece sweater, T-shirt, underwear, socks, heavily compressed.
10. Pump for air mattress.
11. Three spare tubes.
12. Other bicycle supplies: spray bottle, extra toeclips (yes, I know), batteries
13. Sunscreen
On top of that, we add these items, selected to be on top because they're the first things I'll grab when I get to camp, especially when I need to grab the shoes to walk to a hotel:

14. A cheap bath towel. Camp towels and I do not get along well.
15. Shoes for camp.
16. Another cheap bath towel. In case the other one doesn't dry out in time. (Never been a problem.)
17. Shower/toilet kit.
The bag closes easily, and it's nowhere near 70 lbs.