How much beam for "semi-self-tending" setup?

[drawson]

I'm contemplating replacing our staysail traveler with the semi-self-tending setup from The Riggers Apprentice.

The boat is a Southern Cross 35. The existing traveler was approximately 4' long; the staysail boom is approx. 11' and the staysail area is about 150 s.f. The issue is that the only fair lead to the cabin-top winches is from the cabin top itself rather than the side decks. I suspect that I could get the deck blocks as much as 5 feet apart, but that would be it. I doubt it's over 15 degrees off of centerline. At this width, will the leeward sheet provide much vang / preventer action? Are there other recommendations that would maintain the self-tending setup and still provide better control over the sail?

Is this enough width to make a useful modification? The alternative is to replace the traveler (the old one is really dead), but it's about twice the price of the necessary hardware for the semi-self-tending setup.

I've attached a small image of the foredeck - the attachment point for the baby stay is the cross between the two foredeck cleats; the traveler is the heavy line at the left side of the image.

Thanks!

Dan