It sounds like your question has been handled well by these guys, who are always so generous with knowledge.
I also had some "glue" on the rear fender of my 41. I used
Simple Green to remove 90% of it. The remaining 10% came off with my finger nail, then some paint Cleaner. Followed by a good polishing.
Additionally I have found Simple Green to do an excellent job cleaning my Eng., fender wells and undercarriage. It cleans well, does not leave a residue and dries to a nice flat, stock looking finish. But be careful, in a closed environment the fumes can make your head a little "fuzzy." Kind of like 3-4 beers, so they tell me

:grin:
Best of luck,
Michael41