Is have some small patches of wood rot on the underfloor of my Motorhome, nothing serious but I will be cutting out the rot and replacing with new marine ply. I was wondering about using some kind of spray under seal to protect the whole underside, just the wood as the chasis is all in good order and galvanised. I was thinking about one of the Ronseal spray fence/ shed products as these are breathable and. I don’t really want to totally seal the wood. Has anyone used these products with success or have any other suggestions please.