Your concept is basically correct. I ran main halyard, two reefing lines,
the vang, topping lift, and a mainsail downhaul back to the cockpit last
season. I put way more holes in my cabin top than I ever thought I would,
but we did a good job and everything works well with no leaks.
I have six turning blocks clustered around the base of the mast (using two
doubles and two singles), two three-line deck organizers to turn the lines
back to the cockpit, a triple rope clutch to starboard and a double rope
clutch to port. The cam cleat that is part of the mast raising system is
used to cleat the topping lift line.
The only thing I plan to re-do is going back to 1/4" halyard and reefing
lines. I went up to 5/16" when I had to get longer lines, and that's the
maximum size for the blocks I'm using. After almost a full season of use,
I think the 1/4" line would have been fine for the job, while causing less
friction at the blocks. That added friction is the reason I added a mainsail
downhaul. Going back to 1/4" may remove the need for the downhaul.
I don't really have any good pictures of the setup, though the positioning
of the clutches can be seen at http://www.winternet.com/~eric/boatmods.html
-- Eric L. Pederson P-19 #970, Necessity Bloomington, MN