Aluminum roof - bonding options?
I'm getting ready to put a new custom arched roof on my Jammy made out of lapped 18ga or 20ga 4x8 aluminum sheets over lauan on a steel frame, similar to how a school bus is built.
I don't want to use the OEM red contact adhesive since I've read online & been told by my local shop that over time the bond it makes turns acidic and eats the aluminum from the inside. I'm pretty sure this is what totaled the original metal roofs on both my older rigs to begin with. Is this information out of date? Will a newer neoprene adhesive like 3m 1357 not cause this?
My other question was if I should just 'float' the aluminum pieces? Either way I plan to screw/rivet the panel edges anyways. My main concern was that this would leave a small gap where condensation could build up and rot the lauan. I've thought about coating the wood with epoxy before I lay the aluminum down, but I think that would just trap any moisture inside forever and cause more problems.
I'm almost literally dizzy from researching so many different industrial adhesives. Any that look like they would work in place of the red stuff are pretty expensive, difficult to apply or both. Thoughts?