I mounted a CFF300 (about 38lbs) and my 130mm GTX on an 1100 mount. With all accessories I was pushing the limits at about 105lbs. I mounted the DOVELM162 sideways on the mount and then used the 18" SBS plate in that. I then mounted the DOVELM162 on one side (for the CFF300) and for the refractor I used the shorter 10" saddle in order to save weight. The challenge was that I was fully loaded on the counterweight bar as you can see.
Given the diameter of the C11 I think you will need to use the full 18" SBS plate. Unfortunately, the combination of the two 16" saddles, the 18" SBS and the 10" saddle meant that I was carrying a lot of weight even before I got to the telescopes.
It did work but had disadvantages. For one, whichever telescope was on the "down" side barely cleared the walls. Also, the refractor was for imaging but the CFF was mainly visual and I'd often want to use each but at different targets.