I was waiting for a camper rental to come pick it up so I stopped and bought about $80 worth of clamps and clamped the window to the rollbar as instructed. Then I marked the point where the window hits the two reinforcements in the back, and then measured at several points, the distance between the aft edge of the front of the rollbar and the front edge of the window. Eventually, the window is intended to be even 1/32" aft of that point to mate properly with the canopy.
My measurements were weird. It was about 5/32nds at the base on the right side, pretty consistent up through the top and then on the left side it descended to about 9/32nds to about 1/2" on the lower left side. But, whatever.
Then I removed the window. I need to take off 3/32nds (the lowest of the distances) plus 1/32 according to the instructions. So I need to remove 1/8" from the notches. Not sure How I'll do that yet. Probably drilling holes and a cutoff wheel.