If I were you I'd call the owner and say, Listen here, Toots, for the next six (eight, twelve, whatever) weeks I'm going to have someone come over to your property every so often and cut the grass, clean the yard, pick up last April's Weekly Beacon and whatever other garbage has accumulated since the last time my guy was out there cutting the grass, cleaning the yard and picking up last April's Weekly Beacon. I do not expect any reimbursement from you; neither do I expect any interference whatsoever. You may respond with a crisp, Why, thank you Mr Limey or I will make your life as the owner of this rat box a living hell.
That's what I would do.