Kevin , what a project you have ahead of you….(you got yourself a nice bus…have to say I’m a bit jealous and amazed you picked her up for such a great price
When you say “extreme back bathroom” …do you mean it will be at the very rear of the Bus?
This is just my opinion…But if that is what you meant….
You might want to re-think that and have the bathroom forward of the bedroom.
That way visitor’s wouldn’t be walking through your bedroom to get to the bath. Stuff like that is important if your girlfriend, wife or whoever is taking a nap…
I don’t think you have to worry about locating your Black water tanks; hot tub etc up forward of the bedroom…your bus will easily handle that load.
Just a thought…