I may be rather cynical but in my opinion security is an illusion. My neighbor was bragging about a fancy keyless combination lock on his front door (sticks and bricks). I pointed out how I would just take the concrete planter full of his wife's flowers and put it through the sidelight at either side of the door and walk right past the fancy lock. He gave me a funny look.
Look for RV resorts that advertise security guards / patrols, then you can worry about them robbing you rather than some random drug addict off the streets.
A battery powered angle grinder will make quick work of any lock or anti theft contraption. Maybe an RV has a steel door (unlikely?) what is that door set in? A wall that's made from aluminum or fiberglass panels (might as well be plastic) and pressboard or aluminum ribs. A wonderbar (flat crowbar) will either open the door or rip it from its frame surprisingly fast.
ADT and the others offer cellular based alarm systems, you could install one of those so you get an email after the break in, and maybe can secure your property from the passing by looky-lou's who come to pick through the aftermath.
Sorry, kind of in a mood today... but honestly, the best suggestion I have is keep your important stuff in a bank and keep up the insurance payments for your RV.