Re: Super Maramu stern bumper painting
Use paint made for inflatable dinghies. The bumper is made of dense closed cell polyurethane foam. We have used the West Marine Brand with excellent luck by following preparation directions _exactly_. We re-paint once a year and have never had a failure of the paint.
https://www.westmarine.com/buy/west-marine--top-coating-for-inflatable-boats-gray-quart--P010_301_001_501 (Pick your favorite color!)
Anything else will be too brittle and crack off, epoxy will be even worse. You really should use a water based paint, since some solvents can attack the surface of the closed cell foam leaving you worse off than before you started.
Painting this part BEFORE it needs it is key to keeping it protected from UV and having a long lasting, good looking, bumper. They are expensive, and sometime hard to get. Take good care of it and it will last a very long time.