You should expect a lot of late night calls until you can drive the neighbour out.

I had somehow managed to remain oblivious to the fact that neighbourhood association and, in some cases whole communities, banned clotheslines for aesthetic reasons until about a decade ago when friends of ours moved into a new subdivision and erected one.They eventually challenged the neighbourhood association and were allowed to have the clothesline if the neighbours adjacent to their property did not object.  

In some of the oddities of the system our generating capacity, much of which is nuclear, often puts out more electricity than is needed, and so it is sold off to neighbouring US states at cut rates. 

If it is hanging over and overhead power line-call the power company and they should come and cut it back.Call a tree company and post a note on the neighbour's front doors and tell them the tree company is coming on X day and will be cutting any part of the tree that is hanging over the property line.

You have already been informed the neighbour is "aggressive/confrontational".

Do the job, ignore the neighbours, move on.You will not be there long enough to care assuming you are doing a flip.

We like vacations as much as anyone, but our most important travel goals and the reason we're in this involve frequent trips to Greece and Russia to see our families back there.

Reminds me of Greece.

At worst there is a black swan event due to the hyper-connectivity and systemic risk that is present in our financial industry due to the consolidation of the too big to fail banks which could lead to a Cypress-Greece style credit freeze and liquidity crisis.I hope I am wrong but I am hedging my portfolio in the chance I am right.

See Zimbabwe, Weimar Republic, Iceland, Greece, Rome