The Sacramento Northern was a fully owned subsidiary of the Western Pacific, and it's cars were seen all over the west coast and into Canada. They had 100 50' PS1 double door cars with Superior doors. They were basically auto parts cars without the parts racks. http://www.wplives.org/sn/freight.html We would have to have a run of 300 cars or a runner pack...
I would go for at least two each of every road number you might do. Tidewater Southern's Cornucopia scheme would be a good one also.
Tidewater Southern Cornucopia pictures I hope that these links work. I'm not real computer savvy. http://www.elvastower.com/forums/index.php?/files/file/1133-tidewater-southern-516-box-car/ http://www.lafterhall.com/03_027.jpg https://en.wikipedia.org/wiki/File:TSCornucopia.jpg
However many road numbers get released, that's how many I'll buy. (Probably buy two or three regardless.)
Have you tried just contacting MT to see if they would be interested in doing the car as part of their regular run? I've had very good luck with doing that with the NWP cars and Hercules Powder Co cars. This is especially true if you can provide most of the colors and graphics (like the TSCornucopia on the wikipedia page)... Either way I'd be in for at least one depending on the final price.