I'm rebuilding a utility trailer that has a metal frame and plywood floor & sides. I want to paint the wood panels before screwing them to the trailer, for some weather resistance. Last time I used unpainted pressure treated ply and it's lasted 10 yrs, but it's time to renew it.

I'm told by contractors that pressure treated wood needs to dry out before being painted or the water will keep it from sticking. I'm not sure if plywood has the same limits or not. If that's the case, I'm OK with exterior CDX sheathing, but I dunno if just paint is enough to keep it from rotting.

I intend to cover the edges with metal foil tape in either case, so if it's sealed and painted would CDX survive?

If the wood is dripping wet then you shouldn't paint it but if it's just a little damp you can paint it with latex paint. If you plan on oil based paint then it will need to be completely dry.

The treated plywood will last longer with nothing on it than CDX would fully painted.