From your desription of your reefing system it may be able to be rigged the same as our L400:
Third reef line is attached to the sail at the leach .
Runs down to a block in boom at leach end.
Runs through boom to block at the mast end, then down to turn at deck blocks at mast base, then back thru deck organiser to
helm.
Luff part of 3rd reef has a integral tape loop c/w stainless clip, that one clips into a either 1st or 2nd reef eye on the mast.
Notes:
You could tie line on boom and have block on leach end, same as reef 1& 2.
To enable smoother reefing, we have installed 70mm blocks at the tack end of reef 1 and 2, and also at the eyes on the mast.