With a hefty lens it would be the sensible thing to do to use the lens tripod adaptor an let the C100 body hang of it??? Can the mount support its own weight safely?
When shooting with long heavy lenses, I'm going to be on tripod. When I'm going light without any rod setup, I have a long plate for my Sachtler tripod that I attach to the camera with plenty of plate sticking out front, then I have a shim that I put between the lens foot and the front of that plate. I probably don't need it, but it's a little piece of mind and it can keep the camera a little more stable.
When using the rod setup, I have an extra adjustable mount that attaches to the lens foot, so the camera and lens are now both attached to the rods. Takes a few seconds longer to assemble/take down, but again…rock solid.