Welcome to the forum and SkoOliE MadNeSS!
This is a great group of folks and a vast source of knowledge and experience.
To determine our bus
layout we drew an outline of the available floorspace (taking into account the wheel well humps) on graph paper, then, using a separate sheet made cutouts of appliances, furniture, etc. to get a "map view" of the whole deal. There are lots of possible sizes for most things, so you may end up with a lot of little puzzle pieces. But it's a great tool to make sure what you want is feasible.
For some areas we went so far as to cut up cardboard & assemble a faux shower stall and tiolet area -- just to make sure the ergonomics would work out. Since (in our bus) these two items will be against a wall with a sloping/curving ceiling, we wanted to make sure there'd be no rude surprises *after* they're built.
Finally, when we had a layout we liked, we did a similar operation (graph paper w/puzzle pieces) for the profile or side view.
Anyway, we're only putting in the wallcovering, so our superduper layout isn't even installed & tested.
But it gives us a plan & direction.