I think that your idea will have drawbacks in cost and convenience. I say that with the admission that I have presented more than one ill-conceived idea on this forum.
I don't get why your weight is ruling out hard cases for you. FWIW, I am 6'1", weigh 230, and my jacket and pants fit into my 36-liter side cases from Caribou. This is Motoport mesh gear which is kind of thick, plus rainproof liners. They do fit snugly. As far as I know Caribou still offers 42-liter side cases also which may be a bit thicker.
07 DL1000, all farkled up