Go for the ring hangup on the mainsail. Easy to release and easy to get up. Also easy to build/mount. The only other usable system I have ever seen is with a stainless steel wire secured to the bottom of the mast when the sail is raised.

To achieve best performance and the cleanest setup, let the halyard run inside the bolt rope track.

Be careful to isolate all stainless steel fittings from the aluminium! Use special Sikaflex or epoxy as a barrier coat.

Use only monel blind rivets, seal the rivet holes! Dont use aluminium or steel rivets!

Good luck with your project. If you have the time, I KNOW many readers here would like to se how you do this. Please consider making a website and document your project.

Good luck!