I about blew out my o-rings installing 2 65 lbs batteries in my RV, I can't even imagine.
If you beefed up the compartment or are sure its strong enough, I would not worry about the extra weight. My water tank is on one side of my rv (and 100% behind the rear wheels) and I can't tell the difference in driving if its full or empty (415 lbs).
If you are really concerned get to a truck scale and weight the axles and then weigh one side, you can see if your load is really that different. To be accurate you would need the rv loaded like you are on a trip including the human meat puppets.