My daughter used to live in Byron Bay, NSW AU. It's a beach resort/hippy type town. She'd often have 'stealth campers' parked in front of her house. The large trees, quiet street, seemed to attract them. Often no issue, but occasionally noise, litter, and using her yard as a toilet got to her. Easy to spot a 'camper', she knew her neighbors and their cars, so a strange van wasn't hard to spot. I hit upon a solution, I had a red laser pointer. Aimed at the windows of the van from her upstairs window caused them to quickly decide to move on!
I left the pointer with her, was a great dog exerciser too!