I'm not sure if you could work it out, but Gorilla Mounting Tape is amazing stuff. It's maybe 3/32 inch thick. There is a warning on the package that trying to remove it may cause damage/not come off clean. It hasn't let go of anything I've tried it on so far. I used it to mount half-circle fish eye mirrors on my pick up mirrors, with a home made pine wood adapter fit to the curve of said mirrors. (2 years so far) I had used contact cement before with limited success.
You could maybe put it along the inside edge of the cowling, peel off the backing, and work the gasket on to the cowling/tape combination. It's not as unforgiving as contact cement. (instant grip no---second chance), but once you place it and press it, and it cures a little, it wants to stay. Maybe?