There are 2 popular brands of surge protectors: Surge Guard, and Progressive Industries.
Both companies also provide 2 basic types of protectors: portable - in line, and permanently mounted.
The in-line will have plugs at both ends of the protector. You plug it in somewhere between the electric source and your power supply in the camper.
The permanent ones are hard-wired into your camper, somewhere between the outside plug and the power supply in your camper.
I think the biggest difference between Progressive Industries and Surge Guard is, Progressive Industries provides a life-time warranty. Surge Guard does not.
I have had both. My first was a Surge Guard. It lasted a little over a year and then bit the dust. Don't know if a spike took it out or what, but it DID do it's job. It was an in-line model.
So went with a Progressive Industries second time round. But it was an in-line also, and ... somehow it came up missing. To this day, I still have no clue what happened to it. It just disappeared! Really.
So my 3rd one is another progressive, in-line, with plugs on both ends. But ths time, I installed it inside the camper. I cut the 35 foot electric cord and installed a new male plug. I then could plug in the surge protector, located inside the camper, and simply push the male end out the original hole in the side of the camper. I then use an external cord and plug into power. I also kept the original 35 foot cord (although a couple feet shorter now), and put a new plug on the end, and now have the original cord as a spare.
The advantage of doing this is, #1, will never loose the surge protector again as it's inside the camper. #2, if it blows again, it's just a matter of un-plugging and plugging in the original wire, or a different wire. #3. If I ever sell the camper, I can take the protector with ME. It won't be sold with the camper.
Here's how it came out. And it works great this way:
And its all tucked way behind the bottom panel in this cabinet. I added a door on hinges for easier access: