not really much you can do, as even if you add an alarm system, by the time you get there, the damages will be done

you CAN< hide a few trail cam's near where you park, and I say 1-2-3, as they might also see them and take them too, plus more than one, gets you odds of seeing a face in a pic'video over just one cam!
I am rather lucky I hunt mostly all private lands and park truck/trailer at land owners house and walk into stands, Only use ATV for recovery, or setting up stands
and have never had any worries really about folks screwing with it parked in the woods some place!

the sad part of things liek this is, many times its other hunters doing to to fellow hunters!

I am pretty heavy in ATV's for decades now, I know of NO locking fuel caps options either!
its kind of a gamble , carry good full coverage insurance, its worth the cost IMO,
and try and park in places less folks walk past to see it
LEAVE a note on it too maybe saying you can see it from where your hunting at!

a TIP to setting up cam's
if park atv where you can set cams up HIGH in tree's by standing ON atv's rack, out of reach of most folks, then more atv to where cam's are aimed!

we used to use trail cam's when we rode atv;'s a lot and folks used to steal our loading ramps, so would hide cam's watching our trucks(can work here too as not just atv's get broke into in hunting season when your parking in remote places and be far from it)

trick we learned about ramps, was to park truck tires on them, just in case anyone has ever thought about how to save them
Bolt cutters cut l;locks/cables REAL fast and didn;t stop them from being stolen as much a s parking on them did for my group
seems jacking a truck up is more work than bolt cutters!