I've used the the sealed Master Locks without issue for a while. Honestly, I think it comes down to only putting the locks on when you are parked leaving the trailer for an extended period of time. Putting locks on and then running down the road in the snow, sleet, salt and grime, just leads to locks getting messed up, jammed up and froze up. I guess I don't see the point of having the trailer locked while driving down the road ???
I really don't foresee the group from "The Fast and Furious" pulling some daring sled theft while I'm rolling down the interstate..................LOL
Once I we get to our destination and the trailer gets parked, then the locks come out and its secured. Another time would be once we get to the parking lot in the morning, unload, get ready and lock up for the day.
Another reason I'm not big on having the trailer locked up while in transit is what if there are problems and you need to get stuff out of the trailer in a hurry. Case in point ......a fire, which almost happened to us two years ago!!
We had some trailer light issues, stopped in Billings, opened the side door to find the trailer full of smoke!!! A wire had shorted out with the power inverter and almost burned the trailer, 4 sleds and a ton gear. We were almost to the point of running sleds out and I for sure did not want to be messing with unlocking doors, especially if they would have been froze up!!! NOT GOOD!
So getting back, get some quality padlocks and just lock the trailer up when you need to.