Hi
My advice is to remove all the plylining and protector cote the floor and a couple of inches up the sides. Then replace the plylining on the sides and wheel arches but store the ply floor in your garage so you can put it back as and when you replace the van.
You will always have water spillage and any water that finds its way under the ply floor will not dry out and create rust problems.
I have seen protector cote on a plywood floor, and can assure you that over time gets damaged and the boards absorb water. One of the local lads did this and has subsequently removed the ply flooring and protector coated the floor as per above.
Spruce