You likely won't have dead batteries during the time it takes to have a nap, but if you have as yet unidentified phantom loads think about this. Those loads are not likely to be fused or pass through circuit breakers. But in the remote chance they are, just imagine that for every foot of wire between the batteries and the fuse or breakers you have unprotected wiring. We have enough potential sources for problems without having as yet unidentified and likely unprotected wires.

One real problem I have with older coaches (mine is one of them) is as time goes on the owners begin to modify them and sometimes those modifications are undocumented and often not of the quality level a converter or professional shop would produce. Kind of scary.