Re: In-mast furling
Agree with 2ndWind. My current boat has in mast furling and my next boat will have it. Regarding the OP's question I have a Charleston Spar system (now Sparcraft I think) and it appears to have a slot in the extrusion for sail slides. Perhaps yours does as well. Would take some rearranging of the halyard sheave, tac fitting, etc. but seems like it could be done without a huge expense.
Cranes Creek, VA