First thing this morning was to sand the filler (on both sides of the fuselage) that I had applied yesterday. The patch won't be completely invisible, but it'll be much better once primed and painted.

Next, I needed to mark the location where the glare shield should be masked to leave an unpainted band for bonding the canopy. To do that, I need to determine where the bead of adhesive will meet the glare shield. So, I broke out my pack of fondant tools (yes, these are cake decorating tools) and selected a 1/2" diameter tool that I will use to smooth the fillet of adhesive around the inside of the canopy.

Update: A few days later, I repeated this process, but with a 1/4" diameter tool so the resulting adhesive fillet wouldn't be as large

I taped it to a wood stick...

...so that I could reach through the back window and drag the ball around the inside of the canopy at the junction where it terminates into the glare shield.

This left a light scratch in the aluminum which I could trace with a sharpie.

I then masked the glare shield boundary with blue tape positioned about 1/8" forward of the sharpie line.

Scuffed the glare shield in preparation for priming and painting.

I realized that prior to painting, I needed to finish fitting and bonding on the tube onto the aft edge of the glare shield, so I masked the edge off top and bottom and sanded away any existing primer.