Small area to work in or not, you'll probably have to mask it twice.
You'll have to mask the canopy area to protect it when you scratch the area to be painted with sandpaper. Paint has to stick.
Probably disturb the masking in the process.
Mask a second time to do the shoot.
I would mask the large areas first and stay away from the canopy frame edge.
You can mask, using strips along the frame line afterwards.
You could spray the inside with "spray mask" then carefully cut the frame in and remove the uneeded mask.
You could attach the canopy, sand the entire thing, Mask off the frame and paint it.
Remove the mask material then clear the entire canopy.
Good luck