Robatoy wrote:

The whole box came apart with a snow shovel.
Now... for new material. What do we like? (No, Lew, NOT mahogany marine
ply G)

I'm open to suggestions, even those including a painted finish of some
sort. Doesn't have to be pretty.

Some wood dealers in my area sell lower grade white oak "truck decking".

Making a floor and side frames out of white oak would be durable in all
respects. An option would be to add removable side sheathing with
exterior ply, sheet aluminum, etc...