I followed Gerald and other folks lead and added an extra overflow/expansion tank. It took about an hour and cost about $15. Probably the only project I have done on a motorhome that cost under $15 and actually has a return on investment. When I could no longer feel anymore fluid level (using my finger length dip test) in the current expansion tank I would then add some.
I would think that the extra tank will eliminate the expansion loss and eliminate the overflow going to the roadside. This tank is 2.5 Quart capacity and it will fit behind the louver hatch with about a half inch to spare. I had mounted a 1/16th thick aluminum panel leaving an inch opening on each side for air/heat flow out of the Glendinning Cablemaster housing.
I picked up Interdynamics BVR4 2.5 quart tank at Autozone for $9 and some 5/16ths hose for the overflow.
Easy project for us that are not so gifted....
Later Ed
