Joe,
Looking at the picture of your boat, you're going to have a tough job
setting a back stay with that main & that Boom. You'll need to build a
Boomkin and without a flexible mast your gain would be minimal at best.
If you are determine to rig an adjustable mast, you might consider
adjustable Jack Stays (a la Lightning) but remember the "Sow's Ear"
It might be a lot easier and cheaper to install a track and turn buckle
on the base of the mast
If you want to race a good HDCP is a lot cheaper and easier
http://community.webtv.net/tassail/ThomPage
http://community.webtv.net/tassail/Pneuma