The gap you have should be a non issue. Most two piece wings have some samll gap. Question? Did you use plenty of glue (epoxy?) to join the wing roots together? This can be an issue later on.

I would recommend you talk with your friend and see if he has an iron or a heat gun. Shrink that covering down, you'll be happier with the end result. If no heat gun than use mom's hair dryer, it'll work, just take a whole lot longer.