Adhesion promoter would be great, if there is one. But I scuffed and cleaned mine as well as I could, and used spray can glue in that area on the metal part, then the D weather strip. I has not moved in 180+ hours.
Also, I would imagine you know this that the middle section needs to be offset a bit.
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying