I worried over that window for about a millisecond, and then thought about how I'd actually be using that area. When I'm driving I don't care about the window. When I've made camp the bed will be down. I'd rather lounge around on that than sit in the seat, and night is when I'd like to be able to see out that window anyway. For me anyway it's a non-issue.
That's not a hinge. The details are back in the thread somewhere but the short version is I attached flat stock aluminum as a frame to the piece of the ceiling the PO cut out to mount the Fantastic Fan. The piece cut out was way bigger than the fan needed, so I cut the correct sized hole in that piece, screwed the frame to the perimeter, and then screwed the whole mess back into the ceiling. Then I mounted the fan shroud up into the hole I cut.
The best way would have been to glass the piece back into the ceiling to make it whole again, but I lacked the experience or desire to mess with the fiberglass. This was the lazy, quick, easy way to get it done.
I think my battery compartment was tool storage or something. I can see where something used to be mounted to the wall/s, but I don't know what. The oxygen bottle was stored in the structure I modified to house the bucket seats. It was slid in from the rear of the unit via a small compartment door. I closed off the compartment from the seat structure so now when I open it I have work gloves, safety glasses, hearing protection, etc easily accessed.
Ready? Ready schmeady. I'm not "ready", but I'm not going down to show off my junk. I'm going down to steal ideas from other people's junk! If you got a set of wheels and a plan where to sleep, you're ready.
