All I know about the hip pack you use is what the write up says. When I lived in Colorado I used (still do some times) a military butt pack attached to a standard military pistol belt. It is about 400cu. inches vs the 300cu. inches yours has. I carried a AMK Thermo-Lite 2 Bivvy and a military rip stop poncho. I would take it out of it's bag and roll it up and put it in the bottom of my pack then do the same with my poncho, and if you use some compression straps they they pack very small. along with them I would carry an MRE removed from the main bag, and my survival kit including another space blanket. You should be able to carry along the same amount of gear because I still had room to spare. I spent several nights out in the feild with just the contents of this pack over the 4 year that I lived there.