I've never done one that wide.  If you're a Lutron dealer, you can inquire with them... they do custom shades in larger dimensions than you can specify with the shade configuration tools.

I took over a job where two blackout roller shades were stacked side-by-side in a tall recessed pocket.  The two shades were overlapped by about 12-14" where they met in the center and then the left and right edges were in side channels.

I'd never seen this done before, but it worked and had been working for 5-6 years.

If you do find a way to do a single shade, I don't think you'll find fabric that wide so fabric would need to be railroaded.  Since the shade is only 10ft tall, you might be able to use the fabric horizontally without any "railroad" seems.