I don't have a Hassie, but do employ a big 300 lens on my Pentax 6x7 using a double-mount system in which both a lens collar and the camera body itself are
attached to the same solid block of hard maple via threaded inserts; then this goes right atop the platform of a large Ries wooden tripod. Very stable. I also have
a big Feisol carbon fiber tripod with an analogous platform top, when I need to save overall weight or bulk. Avoid ballheads and squirrelish quick releases like the black plague. Look for something solid. The sheer weight of medium format telephotos brings a whole different ballgame than 35mm and its toy accessories.