We finally solved the problem of losing coolant through the plastic overflow tank and radiator cap. After checking eliminating a number of possible causes, Bob Rozak asked if some buffoon might have improperly switched the coolant make up hose and the coolant by pass to the radiator at some point in its history. Turns out the buffoon lives in my house (not Kristi) and that it occurred when I replaced the radiator last year. I switched them back and that took care of the problem. Many kudos to Bob (Wattalife54) for sticking with me and solving my problem.
As we were taking a victory lap with Kristi following to observe for leaks, she asked if my left rear tire was low, since the mud flap was touching the ground. I pulled over to the side of the road and found that the top of the wheel well was resting on the tires (air pressure was 110 and holding). I was able to raise the coach and limp home.
"The beat goes on....."
Sounds like the linkage on the left rear height control valve might be messed up? Should be able to check it by looking in the wheel well.