I feel your pain, we have 2 cats which i love. They are fun and entertaining with little work on the human's part.
But they are indoor cats as it's illegal to have out-door cats in the city. So it drives me crazy when there are neighborhood cats that come up to my bay window and my cats try to attack them, typically this is at 3 am, so all i hear is hissing and if you go out there to break it up, our cats, not thinking will scratch your legs as they try to run to the next window to see the outside ones. I shoot at them with my BB gun, never aiming to kill, but to wound, but i'm a terrible shot. The neighbor actually puts out foot for them, so no wonder they keep coming around.
My only suggestion is, they could be shooting off fireworks or have loud music in the middle of the night, or even worse, park on the street on purpose to annoy you. Maybe you should mention it to her next time she's out doing spring clean up and think about if this is worth loosing the neutral nature of your relationship with her and turning her into a mega B!tch through turning her into the city. Don't they say high fencese make good neighbors?
Another option would be to get some type of dog whistle horn, or something else to scare them away without having to go out there and be seen. Maybe chemical you could put on your lawn that would repel the dogs...
“Always do right. This will gratify some people and astonish the rest.” - Mark Twain