I also had to take my rub rail of my Santana21. Not being able to find a replacement, I sanded mine down to fresh Rubber and faired with thickened epoxy. Then faired again and painted with exterior acrylic enamel . I used a small foam roller for texture. Not perfect but from 5 feet distance you won't see many imperfections.
I'm following your work and I think you're doing a great job on a beautiful little sailboat.