Just finished this step. RV-7 tip-up.
Take a look at the photos below. After a rough marking on the fuse, I trimmed the sides a few inchs below the bottom of the joggle along the side of the fuse, and a 1/2 inch in front of were the canopy transitioned from main bubble to the forward clamp area.
As shipped from Vans:
After initial trimming (with my beautiful daughter/assistant):
It's a slow process, doing the fine tuning, but it is not difficult, just time consuming. The "big cut" is actually just a rough cut (BTW, easy!); you'll do lots of fine tuning of the edge after the cut, as the canopy lays down nicely on the frame. The canopy pieces are very manageable solo once the big cut is done.
The first cuts (shown here) were right through the protective vinyl. Later on, I peeled back the plastic, cut off the excess, and then taped it down so the plexi dust wouldn't get blown underneath during the trimming. Be prepared for lots of plexi dust.
I used a Dremel Saw-Max, rather than the angle grinder and Van's cutoff disks to make the cuts; I found it easier to control.