WOW. Thinking about your problem (and not knowing how your tractor is being stored) one way, as a deterrent, would be to 'padlock' the grill guard. I don't know how but it would/may make it difficult to access the bonnet (hood) latch.
Enjoy the site from wherever in the world you are.
given multiple thefts, my larger concern would be for your tractor at large, or even destructive mischief from a frustrated thief. i'd be looking at alternatives for your vulnerable tractor location. also keep a game cam trained on the area
best of luck, & welcome to the forum