I'm not stuck on trying to sell the Rot Doctor products but I used the 2 part epoxy on 1/4 luan plywood for an old home built TT. If coated 2 or 3 times I think it could remain submerged and not take on water. At the time I used it they had a write up on their web site about a treated osb panel and an untreated one that they left out in their parking lot and the results. Even if you bond formica or something to it, I would consider coating the whole piece first.
I needed to coat a couple small pieces of osb and used the 2 part epoxy by loctite from HD. It was tacky as heck and I rolled it on with a little 3 inch roller but it's holding up well in direct weather. It's too thick to penetrate well like the Rot Doc but it works for small areas.