The thermostat needs to be mounted to the side of the water heater housing (not the top). To do that you will need to use a razor-knife and cut out a section of the EPS insulation the size of the thermostat. I adhered mine with hi-temp RTV. You can try to reach in through the drawer hole or just remove the water heater from the side-wall of your RV.
HottRods work GREAT and I'm sure that you'll be happy with the results... and the LPG savings.
FWIW, I heat my water while driving with AC power from the inverter (via the alternator) and with DC power (excess solar) when boondocking. I almost never use the LPG anymore.
Cheers,
-Mark
