I think if you do a quick search on the Internet you will find you have every right to trim back branches UP TO THE property line.
Of course there are some
odd rules (IMO) w.r.t. Oaks around here, so best to reach out to the owner of the tree. As a neighbor it is best to reach out anyway I suppose before hacking up the tree...
I wish you were my neighbor, I would have you take down the oak in my postage stamp front yard while I am away
