You can rig up a sprit boom attached with a Prusik knot to the base of the mast. With some clever routing, the main sheet has some vanging effect, but this is limited downwind. The problem is that the boom has to be attached below the base of the sail to allow the sail to furl around the mast so it’s hard to stop it from lifting.
After trying a variety of solutions the only one that the only one that has worked (very well) for me is having a twin boom system where the booms are angled so as to be self vanging and are kept away from the mast with a cross piece ahead of the mast located by shrouds fixed at the masthead via a hobie spinnaker mast cap.
See this thread for more details (page 4) and thr you tube link
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