Design stage

Now I have the shell. What do I do with it? On a recent boyscout outing even before I had the bus. I had a bid out on a different bus in VA. A little closer than the one I got but, the possibility of getting it put me into design mode.
  How do I develop a system to live "off the grid" for an extended period of time?
   Battery bank, with intelligent inverter/charger, Switching unit for ground / shore power that will tell whether 110v is available or not.  If 110v available charge batteries. If not available use batteries to provide 110v to the motor home.  Monitor battery voltage to determine state of charge and if it drops below a pre determined level start the generator and charge on 110v from it. Extend battery life by installation of solar panels on the rear roof to supplement battery storage.
  The big nuts to crack here are the cost of a Diesel generator, inverter, batteries, and solar panels.
Every Diesel gen set I have found so far has either been $6,000 or more for an RV unit or a small contractor grade air cooled running at 3600 rpm. The latter of them being loud and weak in power. The more expensive units run at 1800 rpm and are water cooled plus put out 6KW or more of power. Just what is needed to power 2 roof AC units.
  Just yesterday I had the epiphany of what else could be used. I have e-mails out to a company that has and overhauls clip on generator sets for over the road refrigeration trucks. I am hoping that they will not be priced out of my budget range for the build. By manufacturing standards these units have to be rated at 17KW perfect size not to small and not to big. Hopefully not to big as well in size.  Normally these generators are encased in a "frame" that hangs from bolts on the front of the trailer and contains a fuel cell and all the support structure for the engine and generator platform. Since I am using this in conjunction to the bus's original fuel system and intend to encase the unit under the bus I will not be using the frame. I do not have a dimension on the Generator set for space requirements yet.
  The inverter is also on the shopping list. I found that Xantrex had a recall on one of its units in August and called them to see if they had any rebuilt units for sale.  They told me No at this time but to call back in a month or so.