Hitch locks or even a really good chain can all be defeated easily with a battery powered cutoff tool. They can cut a square link chain that bolt cutters can't even dent in about 30 seconds. Taking off tires is a PITA and not very practical. Here's what I did. My trailer has a replaceable hitch coupler. It's bolted on. I replaced the bolts with hitch pins like this:
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McMaster-carr sells a great selection of them of varying lengths and diameters with clip retention cables etc.
Anyway when I leave my trailer I just pop off the hitch coupler and put it in the truck or take it in my SXS. Its easy and takes about 15 seconds to take it off or put it on. Just to make sure someone didn't have a spare hitch coupler with them that matched, I welded a couple of nubs onto the trailer tongue and drilled a matching hole in my coupler so the bolts will only line up with my coupler. In order to steal it a thief would have to have a coupler with the same bolt pattern as mine and then modify it to avoid the nubs.