Depends on a lot of factors, particularly how your neighbor
feels about it.
Laws vary from one location to another, but often you have
some legal rights to use a branch hanging over onto your
property, assuming you can do so without damaging the tree.
HOA attention may depend on the thickness of the wire
you use. I have a doublet up on my roof made from #26
stranded, insulated wire with brown/green/black stripes.
The end ropes are black microcord. When I show it to hams,
we generally have to stand right under it. It is very difficult
to see from the street - until the sun glints off of it just right,
or we get a bit of ice / snow on the wire.
A lot also depends on the the background - harder to see
wires with trees behind them then with a bright sky.
Are you planning that the wire hangs straight down as a
vertical? (Possibly pulled towards the trunk so it isn't
quite as obvious?) Or something running horizontally
from the house? The latter would put more sideways
stress on the branch, which might be an issue, depending
on size and strength.