Thanks for the picture. Seeing two of these elusive lenses at once is a rare opportunity.
Hello! I just wanted to show you a picture made in November 2015 with the Nikon D3X and the "monster" Nikkor 300mm f/2 on a tripod. The aperture was f/4. The lens isn't easy to carry for å long time, but I have the car not far away. At that time I used the Manfrotto 058 Professional tripod with the Manfrotto Proball 469. I think this is an OK tripod/head combination to that heavy lens (only the 1200-1700 is even heavier).
Regarding the tripod support i would say - it works somehow. Used the Manfrotto 058 as my first truly usable tripod, it is designed for studio, and has got 5,5 kilograms so not easy to lug around (OK - just a few metres from the car in your case) stable enough (though not comparable to a sachtler) but somehow prone to (wind) vibrations. My first supertele (600/4) MF weighs 6,5 kilogramms (the 300/2 is around 7) and i was having a hard time because of the ballhead i used then.
I would consider a Ballhead just as an emergency option for a (heavy) supertele (tilting issues) except the Burzynski ballhead (which is very stable but even with this head it is a nuissance to adjust).
my choice for this purpose:
#1 (by far) a fluid video head
or #2 a gimbal (dont know if a Wimerley balances with a 300/2) or Acratec long lens head