Dave: The rule says "to either side" not to both sides.
The rule also specifically states that the cunningham adjustment( main downhaul) can only be "consisting of one line equalling not more than a 2:1 purchase."
The Hobie 14 & 16 downhaul attaches to the floating gooseneck, not the sail itself.
The stock setup, which should have come on your boat, consists of a cheek block on one side of the mast and an old-fashioned wrap-around cleat on the other. The ONE piece of line is tied to the loop at the bottom of the gooseneck, run through the cheek block, back through the loop and tied off at the cleat.
Look at rule 6.1 for additional information.
Part of the new rules proposal for the Hobie 14/16 is a more modern 4:1 downhaul.
Go to the IHCA website, rules forum, May 1, 2002 - Hobie Cat 14/16 upgrades

P.S. The Isotopes use a floating boom also but the sail is loose footed. Many of them have a line or wire loop which runs throught the sail plates, down around the gooseneck. The downhaul lines & blocks are attached to the wire or line instead of the gooseneck. This transfers the downhaul load directly to the sail instead of through the goosneck fittings. This seems to run smoother.