I learned a lot on my first renovation and after living in the RV for a year I got a lot of scheming done.
I've started painting over that painful brown color using a light coffee palette. I'm putting a layer or two of satan water based polyurethane on top of the latex paint to give it better water/stain/scratch resistance.
I've pulled down the ceiling again (photo 1). I discovered that not all the bolts I used to hold my solar panels on were stainless and the high humidity/winter time condensation caused a lot of rust on them (photo 2).
I'm planning on replacing the ceiling with thin vinyl sheets painted using the above technique, glued directly to the insulation. I'm also considering using fiberglass reinforced sheet of some sorts, http://www.homedepot.com/b/Lumber-Composites-Paneling-Fiberglass-Panels/N-5yc1vZbqk5
It's as expensive as the solid oak sheets I had used, but has the perk of being synthetic, so prolonged moisture during the brutally humid winters wont be an issue.