dried sandwich spread sealer?

I'm not sure why take put anything between these parts. Either wind noise/whistles or water and dirt from the tire finding its way through is my guess. Anything that is sticky on the top would be a pain to deal with during assembly. Cap tape is sticky on one side and has a saran wrap like film on the other. If I was going to make my own... 1/8 thick X 1 inch wide weather strip from a local store and cover the top side with shipping tape.