Whew! Quite a discussion. Well, we moved to another spot about 5 sites closer to the transformer. It showed 10V higher than our previous spot. The external surge protector has not shut us off, but my inverter did. One time. I turned it back on and all is well. Hope it keeps up.
I will call Progressive Industries tomorrow. Their web site says they have a lifetime warranty on their products. That speaks highly of their quality. They are highly recommended, by the way. I would not want to trust my quarter-million-dollar-coach to a park's power system without one.
thanks for ALL the advice.