I'd say unless you can find a shop that knows a bit about this particular type of vehicle
(for qualified repairs), or get access to a few manuals for it (to give you some idea of
what goes where, if you DIY), it's going to be almost a full tear down/rebuild job at best,
starting with gutting the rest of the van and then drawing up a plan as to how you want
it to look, and what essential equipment you'll need in it, when it's done. It looks like it
might be easier to strip the van "to the studs", and then start from scratch, like you would
tear down and rebuild an old house, that's located on a piece of property that you liked.
Consider the fiberglass shell at the back of the van as the piece of property you'll rebuild
your home on. You might have to contract out some of the work to experts along the way.
But a lot of it you can do yourself, and I'd start by making a list of "must haves" for you
and then prioritize them. After that, you can start adding the "nice to haves" as you desire.
Here's a link to your batteries, and I'd say they're not deep cycle, but might have been used
to run the 12V stuff in the coach. I see a red wire to one of them which could be a lead to
some sort of electrical panel in the back (somewhere?).
http://www.autozone.com/autozone/access ... fier=97512