With primer ant the right glue it will work!
Hello
Use LOCTITE SF 770 Primer Adhesion Promoter and LOCTITE 406 Instant Adhesive.
Those together are used for glueing very difficult to glue materials.
Loctite has a small "kit" with a Cat no. 19328, if you can locate this ... not cheap, but works good.
Have made two planes with this. Put the rubber onto the wingroot fairing, put some tooth-pick material on the inside, so that the outside of the rubber is laying flat on the wingroot fairing, then apply dropwise glue from the inside, do not forget to apply primer to the cleaned rubber before.
I have done this with the fairing on a table. Let dry over night is best.
You can also do it only in the last 10-15cm at the end of the fairing, where it is prone to come loose.
Good luck!
Dominik