Wood rots, coroplast sags.
Polymetal is polypropylene plastic skinned in aluminum. Typically 3mm thick with .007" skins, but it's available one-sided and Grimco MaxMetal is avaiable with .014" skins. It comes in 5x10ft and 4x12 sheets. Stiff as 5/8" plywood at 1/10th the weight.
Yes it is expensive; but it's fit for purpose.