Has anyone used or seen a mainsheet system with a 3:1 or 5:1 traditional system linked to an internal boom 4:1 system to give a two speed mainsheet?

This would enable coarse and downwind adjustment of 3:1/5:1 by the skipper and fine and upwind adjustment of 12:1/15:1 by the crew.

The only thing that I'm having trouble with is exiting the boom for the fine adjustment. Two options of a Harken ratchet flip-flip pulley under-slinging the boom or some plain through-blocks either side of the boom with a ratchet inside the boom.

I'm trying to cut down on the amount of rope floating around the tramp by reducing the traditional systems amount of purchase. The internal boom system will be sucked into the boom during tacks and downwinds and taut all other times.