Drill a .250 hole through the left track into the deck about 6" back from the roll bar. Watch positioning for penetrating the longeron mid-leg. Make a 2 1/2" long, 1/4" dia pin from stainless tube or aluminum rod with a key ring thingy looped through a diametric hole at one end. Drop it in place to keep the canopy from rolling back. Cheap. Effective.
Pull it out before flight so you can roll the canopy back without having to fuss with pin extraction if you want out in a hurry. Also, it's a pretty good theft deterrent because you can position the pin from outside if you roll the canopy mostly closed on your wrist. Same move to extract it, which would confound a crook, hopefully long enough they'd move on instead of taking the time to figure it out.
John Siebold