More progress, walls and flat ceiling framed in. I went with a flat ceiling for several reasons. I wanted more of a motohome look inside, I wanted a well insulated attic with vent space and I like the idea of hanging cabinets from a flat ceiling. I also gave up about 3" in width to frame in the walls with flat studs. This offers me 3" of fiberglass in most of the wall space and lots of flexibility while I finish the interior. Finished height floor to ceiling will be 6'11".
I plan to cover half of the walls and the entire ceiling with 1/4" Luan from Lowe's. The stuff is actually 0.19" instead of 0.25" so it is a bit flimsy. Framing the walls and ceiling on 12" centers with flat studs where the Luan will be installed will offer adequate support. I also ran a row of blocks centerline on the ceiling to back up the only joint and to provide nailing for trim. The front half of the bus's walls will get 1"X6" T&G knotty pine so 16" stud centers were used from the wheel wells to the windshield.
At the back of the photo is the roof vent boxed out. I retained the original 2 speed fan and roof vent.
My wife took the entire assembly apart and cleaned it up, sanded it and primed it with Rustoleum. The fan motor was loud on high speed so while it was out I drilled a small hole in the rear bearing housing. I then inserted the the red plastic tube from a can of WD-40 and gave it a good spray. I also sprayed the front bearing housing under the fan blades. After lube/maintenance I let the fan motor sit for 30 minutes before operating it.
This knocked the sound of the running fan motor down by about 70%.
Both sides of the vent were closed off with a 2"X4" flat on edge. The front and back openings were left open. This will allow the vent to evacuate hot air not only from the interior of the bus but from the small attic as well. Having a small 5" attic the length of the bus (which will be insulated with 31/2" of fiberglass) will allow hot air from two ceiling vents in the front of the bus (not installed yet) and from a channel behind the refrigerator (not built yet) to vent hot air from the 2-speed roof vent.