When I first bought my trailer I got a surge protector. Later through reading here and other forums I then thought I needed something to regulate voltage. On a few trips I did notice voltage drop at campgrounds to a dangerous level for my AC unit (below or near 107 vac) The only two boxes I know is the autoformer or the power master (that I have) that not only protect with surges and voltage. These units can be plugged in outside or with an adapter kit wired to the inside, mine is mounted inside. These units are costly but a great peace of mind for me.
This was a little long and might not answer your question. I guess if you think it will get stolen then mount it inside. But if it is hard wired if a surge is detected and it be reset or are you out of luck for power. If needed with the way mine is wired It can be taken out of the system.
George and Debi
2006 F250 PSD, 2005 PF30CK