I have an 80mm piggybacked on top of my C11" on my AP1100.  Cameras on both with filter wheels and auto-focusers 7 USB ports.  I use to guide the 80mm with the OAG on the C11 and that works most of the time.  However, during windy nights it could struggle so I placed a second OAG on the 80mm and it works fine all of the time.