I doubt the area is sufficiently reinforced to handle that load; lots of RV shower floors barely have support under them for an adult, and hear about lots of cracks showing up.
Even with support, it would mean a constant supply of water/larger heater and full hookups to use.
I suppose you have a particular reason to think about this, maybe it can be worked out.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired