Yes, I am agree with your idea that it might look lighter due to the tan interior.
I'm pretty sure that it will look even better with your black interior, I really like to see how it turns out with black
I got mine from here: http://www.metrodecals.com/store/html/Products/Carbon-Fiber-Vinyl-4/3M-DI-NOC-Carbon-121/3M-DI-NOC-Silver-Carbon-117.html
In my case, the 48in x 36in was good enough to cover all those trims including door bar.