Allen,
You could try Bleche White (the white wall tire cleaner) to clean it. Just be aware that will probably strip off any wax on the fiberglass gel coat.
After it’s clean, your preferred vinyl protectant should be all that is needed. Again, just be careful of overspray and clean the surrounding gel coat afterwards.
Paul Mossberg
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)