The storage facility where we keep ours was broken into about 5 yrs ago and again about 3 yrs ago. Oddly enough they did not take any power cords off the units that were plugged in. Or any propane tanks. They did take my 50 amp cord, but only because it was in the basement. Did not bother the 30 amp cord I was using for power.
Most units they just forced the basement doors open with a screwdriver or something, and did not even damage the doors. Shows how strong the locks are. Took mostly tools and small items. Did not bother an air compressor I had there.
Did not get inside mine, but two nearby they just broke out the door windows, reached in and unlocked the deadbolt, and forced the door open, and took TVs, DVD players/sound systems, other electronics, and any thing else they could find of any value.
I now have my name and ID number etched and/or painted on everything and serial numbers written down of everything that has one.