Peter, My objective is to convert the C8 into a Hyperstar-only widefield OTA with remote electric focus, and use the new RC8 for longer FL work as it seems to have a nicer field. Until I sold my other C8 OTA recently, i also did as you described when in normal C8 mode. Worked fine. At the moment the Hyperstar is the only scope I have that requires me to go outside to refocus. God forbid I venture outside too often at night
With Hyperstar, there is nothing attached to the back, so I could hang a cheap Crayford off there just to elegantly push and pull the focus tube.
The reason I was looking at something inside the baffle tube to do the job was so I could get a symmetrical 3-point attachment to the back of the mirror assy for focus movement, rather than the normal offset single point. But Marc's comments lead me to believe that with proper mirror support as he describes, the single point mode is firm in focus and is a far simpler approach. And as a byproduct, I like the collimation ability as well.