It is a heavy duty banner material, so you are thinking more "this should work" or "this will work"? :Big Laugh
Maybe also to take into consideration that location is really exposed - combo of salt (50 feet from sea), sun and strong winds.
No way for anyone to tell you that from one picture, but many awning companies use flex face material such as
Cooley, same material we
use all the time for large flex faces, and yes, vinyl will stick to it fine when it's new, but there's no way for me to tell if it's been clear coated laminated, etc.
Also, they may expect to be able to backlight it, most Flex Awnings do light up at night, so keep that in mind before taking the job.
If you think you may waste material and time on this job instead of taking on more familiar/profitable jobs, then I would take a pass on it if I were you.