I lock hte hitch adapter (Tow bars 2" square shaft) to the RV in 2 different ways.. WHY
Well 1 because it came loose once, Near as I can tell a safety cable (Break-away) snagged the haipin and then the big tow pin came out.
The other way because it stabilizes my bicycle carrier (Ant-rattle clip or hitch immobiliser depending on who and when you buy it )
I do not lock the arms at the Towed end, Just the spring clips. (one of which went walk-about on me but I did not loose the pin it locks)
I also carry a much better extinguisher plus training on using them (Something you should get, Mac the Fire guy is a good instructor by the way, I am NOT an instructor, You can google Mac)
Last "RV Fire" I saw the RV had a bit of smoke damage to the outside, I suspect a good bath fixed it.. The tow vehicle however (Pickup and trailer) was toast.
Not my 1st Car-B-Que. but hey.... I was a police dispatcher for a quarter century. And fire was there already when I passed on this one (I have had a couple (2 or 3 forget which) where I made the original call...I'm sure one poor guy was quite surprised when the FD showed up at the Taco Bell where he was lunching "THAT'S MY TRUCK" kind of surprised,, Well, it was his truck) Turns out I was the ONLY one who called that one in per my daughter's Godfather, who was the Fire Dispatcher on duty that hour)