If you see the truck parked, call a tow truck, say its broke down and have it towed, or call the cops and say you think its a stolen vehicle dumped on your property.
Pretty much just be a dick then?
You know anything about tow trucks? IF it is a reputable towing service, they aren't going to tow a vehicle without you standing there giving your info and your keys to the vehicle so they can unlock the wheel if needed. On the commercial properties we maintain we used to be able to call a tow truck, they called police to give license plate info in case the owners reported it stolen, then they towed it. This was only IF you have the property posted. NOW, you have to have the property posted WITH the towing company name on the sign to tow vehicles abandoned or parked with for sale signs.
IF it is Just1More's property, the laws could be different. I am not sure on this one. IF I found a vehicle on MY property, I would think a call to the local police department would be my first move. "Unwanted vehicle" or "Suspicious vehicle" parked on my property without permission is how the call would come in. Want them to arrive sooner? Tell them you are standing there with a gun awaiting owner of vehicle to show up. Or tell them you are warming up your tractor/bobcat/backhoe to move it or hooking a chain to your truck to drag it away. That might speed them up. Although, if I were a police officer I would step out of my vehicle hand on pistol as I approached your cranky ass.