I replaced a wire loop in my main downhaul with one. It goes through the tack of the mainsail, around the boom gooseneck, and attaches to the top block of my downhaul. I also made a slightly shorter loop that goes through the mainsail tack and around the boom gooseneck. That way, the boom floats with the sail.

You can put a loop through the mainsail clew and around the boom to act as a boom bail. If that is too far aft, you can hold it in place with a track-stop. You can also use such a loop as a floating keeper if you have a trackless clew outhaul.