I had this done like 30 years ago at a local boat top/ upholstery shop. The same shop is in business, but now the son runs it and said that they can still do it. Then they did not have to have the trim, but instead they ran a rail system, and put a matching vinyl trim on as pictured below. I don't know if they can still do it, but it is another option.
Also, I am putting a vinyl top on my new project that was not originally that way, but this time I am using original trim on the back. The shop knew I was having it painted and said not to make it pretty, just make sure it was sealed good, since he had to scuff the roof to help the glue adhere to the vinyl top.