Similar problems when hiking. Saw a Lowepro pac that a nearby pro had. The backpack top held stuff like clothing, lunch, etc. The bottom had a zippered lower section that held camera body and lenses. This lower section could be opened without opening the entire rest of the pack. Thought I might look into this myself for day trips. Currently I have an older Tamarac backpack (can't stand) that does not hold everything I always want. It is heavy, cumbersome and a pain when I want to get at something quickly. I think the newer packs have better construction and lighter weight. I have a smaller waist, shoulder type pack from Kata that works fine for shorter trips when I don't have to take a lunch or extra clothing or a lot of extra equipment.