This was the plan for the layout for the utilities.  Life is easier if you use a control unit like the PMS3 in which case the electrics are all wired in and out of the control unit.  I setup a test rig outside the bus so I could test everything was working
A couple of observations:-
  1. The fridge needs two 12v connections, one to power on 12v (when driving) and the other for the ignition switch.
  2. You need several holes in the floor below the utilities, one for waste water from sink, one for gas compartment escape, one for emergency water drain from Truma and one for cold water inlet from fresh water tank.
  3. The Truma has a thermostat - site it away from the hot air vents
  4. The PMS3 charges the Leisure Battery from either 240v connection or split charge relay (prevents utilities draining main bus batteries) from alternator
  5. The gas flues need to be above the fridge/boiler (hot air rises).  Watch out for open-able windows above flues.