Hi! I believe I picked it up from the factory in June 2013. Interior width, wall to wall, is 78". Length from back end to the new cabinet is 9'4", and from there to the nose is a bit over 5' (for queen mattress). The walls are pretty smooth and can be washed with a rag, painted, whatever; there's no fur or fabric on them. They could use a good cleaning right now, actually.
A decent shop could cut holes wherever you liked and install A/C,
windows, and vent with fan if you wished.
Lil Snoozy has nice outer enclosures for a room A/C, and I imagine they'd sell you one.
I'm in Broken Arrow. I'll drop you an email with contact info.