AZjeff
$50 Site Donor 2023
If you have an HOA, check the rules for signs and parking.
If it was HOA 1) highly doubt there'd be a dirt lot beside the house 2) likely nobody could park there off of the driveway.
Sounds like the bottom line for the OP is he has to take some action IE appropriate signage notifying the public it's private property, no parking allowed, violators will be towed at their expense. Roping it off seems like an easy fix when he isn't expecting any company but that's not an acceptable option.
Good luck getting it resolved. Neighbors affecting your quiet enjoyment of your property is certainly annoying, neighbors using your property is another level.