The 8/1000 is indeed huge, heavy (in its metal case, 18kg), it has its own handle on top of the lens to move it, and I had to have Arca Swiss make a large plate to fit to the tripod holder at the bottom, with its 2 screws. On the Hy6, somehow it does not like it when putting the mirror down manually before taking the shot (gives weird pictures), but using the self-timer works (less movement blur than using remote only).
If someone has the SL66 version, I’d be interested in discussing that filter holder that is mentioned in documentations, so I can check if it is the same on the PQ version.