Here it is.

I've not yet mounted the outhaul, or even settled on the design. Suggestions?

Oh, I've not cut the red line to length yet. I'll do that the first time I use the system.

Careful observers will note that the aft internally-mounted cheek blocks are co-axial, but aligned differently. Each is aligned inline with the expected loads. (One is vertical, and the other is tilted 45 degrees aft.)

The Ronstan cheek blocks were a perfect fit inside this Sailcraft extrusion. The aft large sheave is a Harken, and I used T6061 1/4" AL plate to make the aft fairing.

See my earlier diagram to get an idea how this system works.

All internal blocks are mounted with screws all the way through the boom, and internal Nylon spacers, to prevent line snags inside the boom.