My masts are 47' long with only 3' of bury. The diameter at the base is 10".At the mast head the diameter is about 6"{not going up the mast to find out excactly} At the base the wall is 1/4" thick. Each mast consists or three tubes of diminishig diameters .I do not know now if the wall thickness decreses with each tube but I would think it does,                                The sails are slab reefed and fold up like an acordian . When lowered there is of course a substantial gathering of sail at the tack,but it  is no trouble to secure the flaked sail to the boom with fitted bungee cord ties.THe good thing is the sail can never get stuck as there is no track.The bad thing is in a breeze it is alot of sail cloth for onr person to handle.I had the same concerns as you about wether or not a sail with a zippered luff pocket would fold the same way but I have seen pictures of James Wharrams soft wing sails with zippered luff pockets flaked nicely.             I believe my current masts are about 360 lbs It seems incredible that you can build a mast of similar dimensions at 110 lbs Do you think it would also be possible to reduce the diameter of the mast section.I know that the carbon feestanding mast on the wiley cat is narrower and taller. Attached is an idea I had for battens for a  ballanced lug sail with a luff pocket .The idea was that down haulls could act act on the rings with in the wishbone cambers allowing the wishbones to rotate and the battens  to maintain leech tesion when reefed, It might work on a  marconi  mainsail with a luff pocket full battens and you cup camber idea. Regards Tim