I set up the side wall supports to take this 1 and 1/2 by 3 support, long ago. So that the bottom of the bay joist will all be on the same plane. When I get done I will cover them with alluminum skin and insulate the bay floor with spray foam.
Ive been a cabinet maker for over 30 years now. I suppose some would call me a profesional cabinet maker as I make a living at it. I cant wait to get to the interior of the bus for this reason alone. Im going to do it up like the big boys do it.