if they really want it
there is nothing you can do
when I had my atv on a trailer stolen
it was in a locked gated fenced back yard
the hitch was locked plus the locking ball was inside the hitch
there was a chain through the rims
in my mind there was no way no how to take it
they backed up to the gate tipped the ramp on the car hauler, tied the winch to my trailer , winched it up onto the truck right through the gate and gone in 60 seconds
I now have a complete camera dvr system watching it, it will not stop them, but maybe help catch them