If you have checked all of the items suggested by members of the forum, and if you have pulled the radiator and had it checked for blockage and still found no problem. You can take a couple of steps to increase the cooling capacity of the package. One is to replace the heater valve with one that is a bypass valve (meaning that when the heater is off there is still flow through the heater coolant lines). If you can't find a valve that will work with your heating system then install a cable controlled bypass system ( 2 tees and a old time heater valve). This should solve most overheating problems.
In more extreme cases, add a radiator behind the airconditioning condenser and feed it with the heater hoses, you may have to include a shutoff valve in order to get enough flow to the heater core to heat the coach. Measure the condenser and fan width and check auto salvage yards to see what fits (try Ford Explorer).
These are measures to explore after there is nothing left to repair and the unit is out of warranty.
Earl
