I guess the safest way to put camera in that position is to use Dutch Head. You can rent it in some well equipped rentals. Then you have 3 axis with your tripod head. It's safe, we've used it for Alexa, worked just fine.
I'm looking for a tripod (or head only) with capacity of 15-20kg. Best would be Sachtler 20p or similar (18p, Miller Arrow 55, Oconnor 1030). I live in Poland so offers from Europe would be great. Regards!