It's not uncommon for "fine" or gallery artists to moonlight doing large scale work like murals or, occasionally, scenic painting. (One painter I know does it as a sort of charitable help-theater! donation because, of course, the pay is terrible compared to rich folks' decorating fees.)
Since I've recently been asked to recommend artists who would feel comfortable working at a large scale (yo! theater!), this morning I've been going through old contact lists looking for emails etc.
I found one painter's very cool website: CatheyMiller.com
Painting by Cathey Miller - copyrighted! (also sold)
I was lucky enough to have her paint a couple wonderful circus-sideshow-like banners for my show Slasher a few years back. Made the set.
Slasher, Kitchen Dog Theater