I too recommend the Progressive Industries. I purchased the hard-wire version, but then installed it in my basement where the elec. goes into the coach as if it were one of their portable (i.e. stealable
Following others' advice here on the forum, I "converted" mine to a pseuto-portable by bolting it to the inside of the elec. basement storage area, and installing the appropriate 50A male and female plugs/pigtails. That way, if I am unfortunate enough to somehow fry the PI unit, I can move to another camp ground with reliable electricity, switch around my plugs so that I bypasss my (now dead, hypothetically) PI surge, and still finish out the weekend--albeit without surge protection until I'm able to get my PI unit replaced.