I did a lot of research on surge protectors.
Because you do not
have AC, consider making your own. Here's one thread started by me.
Make-Your-Own Surge Protector
I suggest you scroll down this page as there is a post which has a copy of the original Casita
Because I do have AC
[and have to worry about low voltage as well as surges], I ended up getting a SafeGuard Portable 30 AMP Unit. I got it through Adventure RV for a fairly good price. http://www.adventurerv.net/portable-...mp-p-2763.html
I also bought a 30 AMP 25 foot RV Extension cord so that I can lock my surge protector in the cabin. http://www.adventurerv.net/amp-power...rd-p-7098.html
This combo has given me much piece of mind.
It is preferable to get a portable Surge Protection device over hard wiring something to your trailer. If and when your decide to trade up to another trailer, you can take the surge protection unit with you. The extension cord allows me to keep the protector out of sight and in my trailer.
It takes me about 5-10 minutes to unpack the surge protector and extension cord, plug it all in, and verify the safety of the hook-up. (If the current is bad, there is no point to hooking up the water and sewage line.)
As I said, it is one of the best (dual) investments I have ever made for the trailer.