I also found that switching to an ultralight (or near-ultralight) style also made it easier to keep the pack in the tent. Partly that's because the ultralight pack itself is smaller. Mostly, though, it's that I don't carry very much other gear anymore, and so I don't have to find a place in the tent for it. The only gear I carry anymore is the tent, pad, and quilt (self-stowing), kitchen and food (hung from a branch), water bottle (Sawyer filter stays in pack pocket), first aid kit, repair kit, map and compass, and TP kit. Those all store easily in the corners of the tent by my head. I usually wear most of whatever spare clothing I've brought while I sleep (under the quilt, which is smaller than a sleeping bag); anything I'm not wearing, plus my rain gear, store in a stuff sack which gets used as a pillow under my head. So, there's usually plenty of room in my one-person tent for the pack.

Of course, it also helps that I don't move around much in my sleep!