For protein, I like the foil packs of tuna, salmon, chicken. Lighter than canned both because of the container and no liquid. Also canned sardines.
I've also cooked hamburger, then dehydrated it. It keeps really well (I've used it after a couple weeks) and cooks/rehydrates easily. Many vegetables also dehydrate well, such as zuchinni, green beans, tomatoes, etc. I can buy freeze-dried mixed vegetables at a chain grocery store here (Fred Meyer). The mix isn't strictly paleo though; it includes corn and peas.
If you don't have a dehydrator, you can use your oven set on very low heat and leave the door ajar.
For carbs, you might need to resort to some instant potatoes or something (not strictly paleo, but I think better than ramen). Nuts and dried fruit are good. You could make your own pemmican (dried meat, fat, dried berries) or purchase. I think US Wellness has pemmican made with grass-fed meat.
Again, not strictly paleo, but some good, extra dark chocolate is almost mandatory on my backpacking trips. Also some good, aged cheese.