Best bet would probably be a marine upholstery shop. When I was at SEMA I saw a mini cover that was from a marine shop. Look forward to seeing the finished product.
I would check with maybe bushwacker to see what they used for their sema build. Not a tonneau cover but prolly better in the long run, plus I think it looks badass.
When I'm out and about, people are always asking "what is that", or "Is Jeep making those now". The best is when a 4 door jeep dodges through traffic to catch up and give me a thumbs up as they go by.