I don't know if they are still around, but in the 80's I saw kits to repair vinyl seats and dashes, and a guy that repaired seats was so good you couldn't find the repair. I would think this would be an excellent repair for the roof.
The top material has threads in it for strength. You need to glue in a patch behind the area that is in need of repair then use a product like permatex vinyl and leather repair.