Thats sucks. I travel with my boats a lot and hear is what I do.
* Locked hitch and locked on ball.
* Ball nut is welded so it dosnt come undone and nobody can loosen it. We have towed quite a few trailers in that lost the nut and the ball came off. I remember 2 jetskis went into the woods that were destin for the AC boat show like 5 or so years ago. Brand new and destroyed!
* Cover the boat at night...not while traveling. Cover will dull gelcoat or remove paint. People will remove things from your boat. I remember a trolling motor being stollen at Lake Anna when I was there a few years back.
* My gear comes inside...even for one night.
* If I cant park the vehicle with the trailer in view in a good place I unhook the trailer and park it in a regular parking spot.
* When docking where you stay...take EVERYTHING into your room. Done leave Anything on the boat...especially the key.
Hope this helps...