putting on floor tomorrow

ok heres what I have planned for my floor in the morning. 3/4 ply bolted directly down to the C channel frame. Since its a bolt together frame, and I already welded all the joints, I'm going to take out all the top 3/8 hex head bolts and replace them with 3/8 carriage bolts. I'll counter sink them slighty so the heads are flush with the floor. I'm planning on using roofing cement to coat it underneath. It claims it dries to a rubbery texture which is what I want, I think, how does this sound?
Art
Art