I use wide straps to hang the kayaks upside down supporting the boat on the cockpit rails where there is good rigidity.
Hobie sails are meant to be used on the Mirage Drive boats -- the Drive fins serve as a centerboard. All the Mirages also have a mast sleeve to set the mast in. I'm sure you can rig something up with a home made leeboard (like the sabots use) and rig some stays to support the mast (You need to fashion a mast pocket of some sort as well. The Hobie inflatable sail kit comes with stays.
Your other option is to buy an aftermarket downwind sail -- there are a few different brands. They are easy to use and can be deployed and stowed without too much difficulty.
Welcome to the forum!
