Probably not too helpful for you now, but, when I had my vinyl roof put on I took it to vinyl roof shop. I picked out the pattern and explained where I wanted the overlap to go on the roof. A day later, it was done. From what I remember it wasn’t all that expensive, roughly $150 to $200.
Just throwing that out as an option. These guys do it for a living; they have the proper glue, they know how to prep the surface, they have the clips, and they can lay the vinyl down straight and even.
Please let us know how it works out for you.