That panel looks nice. Masonite is not my favorite material. . . if you could get 1/8" baltic birch, that stuff is really the shit for what you're doing- around here the hardwood/cabinet maker supply place has it for $10 per 5'x5' sheet. The other option is (nominal) 1/4" birch ply in 4x8 sheets, it's usually more like 3/16" or even a bit thinner, it's definitely not 1/4". Have you tried any panels with a thin foam behind the fabric or with the padding you got?