security cameras/alarm for truck camper

A lot of camera DVR recorders use a 110v to 12v converter, and the cameras are also powered by 12vdc. I've installed several in houses. So...you should be able to connect them directly to the 12v system rather than the 110v just to then have to convert back down to 12v. I had a spare security cam kicking around and used it as a backup camera on my previous truck for several years...worked fine.

On analog systems, you can use pretty much any camera you want, so long as the resolution of the recorder is higher than the camera plugged into it. Digital/IP based systems would be cost prohibitive to use in an RV.

The cameras draw extremely little amperage, 4 cameras can run off of a 2amp wall wart even with infrared LEDs. As I recall, the last recorder I put in had a 3amp 12v converter, so 5 amps total if you wanted the whole works. Normally, that's not much, but if you're boondocking off batteries, 5amps all night long can wear down batteries.

Think of your neighbours

Not everyone wants to be awoken at night when a skunk (raccoon, coyote, etc) walks by.

I installed a Starlight LED porch light with a motion sensor. Puts out a lot of light, and comes on if anything moves anywhere around the rig. If someone wanted to, they could install them in place of other outside lights.