Good fences make good neighbors.... either that or concertina wire....
I just had to....
I've had similar issues over the years with an alley behind my property that was used as a dump, auto wrecking yard, storage etc by the rental tenants behind me. I finally got the property owner on board and it is pretty much resolved.
I feel for you, but it looks like you are in a can't win situation....your a$$ owns the place....