That much loosening, I would not call normal. Loctite should help. Unless the AC itself vibrates during use, causing bolts to loosen, I'd wonder about the whole trailer vibrating, from driving too fast on very rough roads, or possibly a suspension issue, maybe tire/wheel way out of balance.
Ask the wife to ride in trailer for a while, see how it rides, any vibration etc. Just don't forget she is back there, if on a day long trip! ๐
Jerry