[Charli]

Just ordered a Progressive Industries 50Amp hard wired surge protector from Amazon. Should get it in a week or so. I removed the rear wall in the storage compartment under the trailer and it looks like the main cable runs from the back of the trailer along the belly and comes up under the interior stairs and then runs to the main panel. I'll cut the cable where it comes up under the stairs and insert the surge protector. There is a plywood floor for mounting and being close to the stairs I can mount the little monitor on the inside of the stair riser so I can see it from the inside of the trailer.
Sound simple and should take less than an hour. That being said simple projects like this usually take a day or 2 with lots of blue smoke.