I use a product called Foto Frisket. You can find it in an arts and crafts store( i.e Michael's in the art section). It comes in a pack of 10 8x10 sheets.
This stuff has a low tack adhesive on one side, strechable to a point and is clear once the backing paper is peeled off.
After you dip the canopy in future. You cut a piece large enough to cover the entire canopy peel the backing off and form it to the canopy.
Because this stuff is clear if you take a new #11 blade you can trace the framing of the canopy and just peel the strips off as you go. Burinsh it down and if you are worried about the paint bleeding under you can apply a little future with a brush around the edges.
I have left this frisket on canopies for weeks at a time and when it came time to peel it off it no residue what so ever.
Hope this helps
Paul