Replacing plywood flooring

My 5th wheel has suffered water damage in the large storage belly on the left side due to lousy workmanship by the manufacturer. The "wall to wall" vinyl floor covering I discover after feeling the mushy floor and removing the perimeter metal trim strips and a wall that conceals the piping, was cut short of every wall by 1/2" to 2 1/2" and no chalk was ever applied. Thus the water that dripped from the pipes (mainly the shower drain) did not come out under the wall on top of the vinyl to be discovered, but rather, was absorbed by the pressed board product.
And I'm beyond warranty by 18 months, naturally, and the manufacturer "declines involvement at this time".

Can I replace this with a good marine plywood? I know it will add a little weight.