I would move the TT to a place on your property that is not so easy to hook and go. I don't know about the area you live so hard to say about theft but why make it easy. Since there are several fresh butts there, someone was looking at it for a reason.
In the winter here I'm home 99% of the day. I have a hitch lock (easily defeated) and a cable lock through the wheels (also easily defeated with a cut off wheel), X chocks between the wheels and tight quarters to maneuver the TT. I don't really worry about theft because its insured but I think about anything in my yard whether a trailer or tractor implement that could grow legs and walk away.