To help
rid your rub rail of creosote, have you tried diesel fuel? It might help, then all you have to do is get rid of the diesel fuel. I would be very careful with organic solvents like MEK, MIBK, acetone, benzene, as they will disolve the rub rail material easily and quickly. They will also do a job on the gel coat or glass.
If you are really worried about it, did you think of getting some of the white shoe liquid polish that they used to use for nurses shoes? Or, what about some KILZ oil based primer. Personally, I wouldn't worry about it that much, but I can understand you wanting to get rid of it. Good luck, Tom