The only way to never delaminate is to not use lamination to make the sidewalls in the first place. A laminated sidewall simply glues (bonds) a filon (or similar) outer layer to a luan plywood inner layer. The type of material used for the outer layer makes no difference - delamination occurs when the glue fails or the inner plywood rots. Ergo, if you want to guarantee no future delam, you have to build a new sidewall without any glue or inner layer.
What manufacturers are giving a no delam guarantee? I know Newmar does because their sidewalls are not laminated construction. Airstream too, I think. Others?
