I have not logged onto this site for a while, but you have asked the question i would love to know the answer to. I would read the instructions on the vinyl
paint regarding surface preparation. Also try to find an expert on the
paint and discuss your idea. Maybe try a test piece. Something like 1m² and a small can of
paint.
I'm fairly optimistic that your plan would work. However, installing the Ensolite will not be easy. I get the impression that
Trillium had a jig for the job. The edges of the Enosolite panels seem better glued then the middle. The up side is, if you want more insulation, Ensolite is
sold in various thicknesses.
I'm guessing that doing it on a hot day would make the Ensolite more pliable and stretchable. It would also make the job a bit hellish.
I would consider installing the Ensolite and then
painting it. At least that way the paint is not being stretched.
Please take pictures. May the Force be with you.