I just bought a used jet ski trailer to use so that I can launch by myself. I put 2x6 boards across the bunks and carry the kayak on those, strapped down. I load the kayak so the rudder is in the rear and so are the scupper holes. I slide the yak back far enough (right side up) to put the cart through the scupper holes or put it in the water if you are close enough, attach the cart and slide it the rest of the way. Could you leave the drive in before launching off of the trailer? As far as steering, could you put some sort of rod, screwed into the top of the rudder lever that goes across her lap to her right arm with a knob on top. she could use her right arm by moving her hand left or right and the lever would move the rudder lever. Perhaps, use a wooden yardstick or round piece of delrin plastic. hopefully it wouldn't interfere with her knees and peddling. Just a couple ideas.
2011 Sport Mirage