I had room in an empty section of the wall where the electrical cord came into the camper.
When I removed the panel, there was a junction box located there. It was just a simple matter of installing the surge protector on the wall of the compartment, then routing the wires thru it and back to the junction box.
If you have such a place even if there isn't a junction box, you could break the line and route it thru the surge protector.