30 pounds is the high end for frameless packs and that usually means packing them so your sleeping pad forms a column to aid weight transfer. 20 pounds is more like it for most frameless packs.
Some packs use a plastic sheet, others aluminum stays, and some more exotic stuff like fiberglass wands (Dana). It's all a game of getting the weight off your shoulders and onto your hips.
Lightening your load really solves the problem. If you are carrying 50 pounds, something in your body is going to take the beating-- your knees, ankles, feet-- and it takes just as much sweat to haul, regardless of the load transfer.
The question is: why would you want to carry more than that anyway?