Oh, man, I see you are really desperate.
I saw your multiple tries to find a partner, and although 2 months ago there were 2 other guys from Greece, it seems you found no one (maybe they partnered up by now and left).
I was thinking of writing to you, as I live in Serbia and do speak (some) Greek (although I don't write), as I lived for 13 years in Athens.
But I have not psychologically made peace with myself, am lacking resources for any easy method (like gun or even SN), so I chose not to give you a hope unless I can deliver.
Today you opened a thread on buying SN in GR.
Now you ask for full suspension hanging.
I hope you find your method and find peace.
If you're still around in a month or so, maybe I'll be ready as well.
A tree is OK as for your question, I don't know in which city you are, but if in Athens you could use Likavito or one of the woods surrounding the city.
Heretismous apo tin Servia. :)