I used just an eyestrap ti which I tie the green line with a slip knot. Like that it comes off very easily even when alot of downhaul tension is put onto it. Jam or cam cleats tend to let the green line slip or strip the mantle of the core. Eyestrap is best in my opinion. The VWM Blade has a sail hook on the end of the green line that hook into a hole on the base plate.

62 inches sounds like alot but with thsi 12:1 system you can REALLY downhaul your mainsail. I'm getting 5 to 6 inches of downhaul between tensioned and fully tensioned. When the sail is slack it is something like 10 inches. This mains the blue line block needs to travel 60 inches inside the mast. Either that or you need to pretension the setup but repositioning the slip knot in the green line. My setup is just a little too short to go from fully slapck to fully tensioned and so I use this slip knot trick to preset the tension or the conditions I'm expecting. I can even do that easily on the water and have.

Wouter