It's for this very reason I never wanted a hard wired EMS.
On my previous travel trailer (Keystone Outback), someone "borrowed" my portable Progressive surge protector (If you know what I mean). I'm hoping someday, that some one will return it? But probably not, never! especially since I don't know who that person was!)
Meanwhile, I decided to go a different route when I purchased a new one. I accessed the junction box where the umbilical cord attached to the main wiring and cut the umbilical cord enough to put a plug on it. That way, I could plug the new portable one, to the now short one, plug the new protector into that and shove the over end of the cord for the protector through the mouse hole. On the remaining 35 feet of umbilical cord, I attached the opposite plug and continued using it as my power cord. This way, in the event of failure, it was simply a matter of unplugging the portable protector and plug the original umbilical cord back in.
When I traded the camper for my current Montana, I simply pulled the protector and plugged back in the umbilical cord. I did tell the dealership what I did if the next person ever wanted to put a different protector there.
This is something you may consider doing. Attach plugs to the hard wired protector and in the event of failure, you can simply unplug the protector and plug directly back into shore power. Or ... use a portable one.
On my current Montana, I don't have a way to access the junction point, and not sure where even is. So, I'm religated to using the portable one at the shore power post. I do have a bicycle cable attached and I keep it locked now.
This is the other end of the surge protector sticking out the mouse hole. I used a different 30 amp cord (longer) plugged in, in this photo:
My current EMS, purchased it the day we took delivery of our Montana. It's been plugged in every since!