The "Goop" will work but it usually looks like hell when it's dry.

The RC-56 works very well. As another said, shake the bottle or stir up what's sitting on the bottom and it thickens right up. Most people use waaaay too much RC-56 when they install a canopy and it runs all over the place when they do. The secret is to rough up any covering where the canopy will sit with some 150 grit sand paper. Use a thin bead of the RC-56 and tape the canopy in place for 24 hours or a little longer. It dries even faster if you drill a 1/16" or smaller hole somewhere in the canopy that's not going to be obvious. Vents the moist air if you have a sealed canopy/deck section. Wipe off any excess with a water dampened paper towel before it dries.