Are you talking about a A-Liner type trailer?
I think that those are more secure while open and the door is locked. There is not a way to close it from the outside, nor open the top and climb in. Any RV, you can break a window and climb in, that is how they broke into my class A motorhome while it was parked in my driveway. The police say that sometimes they smash a roof vent, and lower a small kid into the roof vent to open the door for them.
At least when they broke into my motorhome, they took a TV, VCR, couple of blankets and some other stuff, but really did not to much damage, just had to replace the door window and it's frame.
Then I spent about $1,000 on a fancy alarm system, with remote pager that will page me if I am within 2 miles of the RV. Still nobody has broken in after that install!
Fred.
