Meguiars has a line of boat polishes and waxes. They are all I use on my 1983 Classic Roadsters Duchess (pictures in the PMOSSBERG folder in the Gallery).
Start here at http://www.meguiars.com/estore/ and click on Boat/RV Care.
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)