Get a ring doorbell and mount it under the dash. Pain in the butt, but you could connect it to the wifi at the hotel and if anyone gets in or
near you'll be notified and you can tell them where the club on the steering wheel will be placed if they don't leave.
If you want a cheap LoJack, buy a cheap burner phone. Buy a month of service, Install an app called "Find My Kid", fully charge the phone and put the phone in the trunk or under the back seat etc.
The app let's you activate the ringer, I think you can even talk on the phone without someone having to answer ( IIRC, so don't quote me on that)
