Having been in the security business for about 40 years (
http://www.advancedcommsec.com), I've often thought about putting a security system in one of the various campers we've owned (2 motor homes - one travel trailer & now a teardrop). I never did and although we've camped in all sorts of different campgrounds, I'd never heard of a single break-in.
IF I were to install one, I would go the wireless route rather than running wires through the camper. One downside, everytime you'd unplug from 110VAC the control panel would start beeping the keypad to notify you of the power loss. You could simply disconnect the standby battery to stop it or perhaps install a toggle switch to disconnect.
My feelings are, 99.9% of the folks you encounter camping are the kinda people you don't have to worry about breaking into your camper.
Terry s