Well, I guess it depends on how well they actually seal and if you have any other violations in the metal. Don't forget the tail gate seals, especially the one at the bottom. If you plan on doing water, you might want to consider removing the flooring material and using something like Rhino Liner on the floor. then it won't matter if water gets in or not. How deep of water are you planning on? You can't go too deep, don't forget you have all kinds of electrical stuff that is exposed.
Good luck,

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