Excellent answer, Wolfen! The fact is that even going only as deep as the floorboards can/will cause problems further down the line because, by doing so, you're necessarily flooding a whole bunch of electrical connectors, switches and circuit-breakers, and they'll start corroding the moment you get out of the water and, typically won't short-out until sometime later; right at the worst moment (not that there's ever a good time to have electrical problems/failures). My two-bits........
P.S. Another thing to consider come time to sell or trade your RZR, I would NEVER even CONSIDER buying A USED RZR that had been submerged above the center of the wheel-hubs, cause I'd know that, sooner or later, I'd have problems with it, for the reasons stated above.
Cheers