Either Progressive or Surge Guard will do what you need - but not just their lower priced surge protector models. You want the more expensive surge/power protector. It will shut off power if the power level drops too low or raises too high protecting the electronics in your coach. Portable or hardwired? Both work the same. If there should be a surge either of these companies units will blow as they should protecting your electrical system BUT then they no longer work. Progressive lets you send the unit to them to be put back to working order for a significant fee. Surge Guard tells you to buy a new one. So a portable in this regard is easier to deal with. Surge Guard sells a locking cover to prevent theft for their portable units.