As for your rear bath question: I can't imagine any likely scenario where that would in itself cause a handling problem. It does imply that holding tanks are at the rear and sloshing stuff in them could in theory be noticeable, but RV tanks are not really big enough for difficulties in practice.
The only driving drawback I can think of for this layout specifically is the impossibility of having a back window. With a stick-on wide angle lens and sightlines from the front, the window can be nice. A rear view camera is a viable (arguably superior at times) alternative. Of course, one can drive safely with just the outside mirrors, but more visibility is never a bad thing.