Hi Charley

For the Hobie 20, have Skip Elliot build you a spinnker, the Tiger spinnker is not big enough and won't be as fast. The Skip Elliot sail sheets to the side stays, using two ratchet block each side. This allows the crew to hand hold the sheet even in high winds. For the spinnaker pole use 1 1/2" to 2" anodized aluminum tubing. Have your local sailing shop build wires for the front, old trap wires work well. For the snuffer ring and bag you can build your own or buy a stock system off a production boat.
The sail hoist point needs to be below the top of the mast about 3 ft. If you need it I can send you my measurements.

Sail Smart

Scott