I think many people use two ale pails or carboys. I know it's not one fermenter, but it's manageable if you need to move them, and a 12 to 15 gallon (keep in mind you'll need head room for the fermentaion) fermenters are expensive compared to a couple buckets. I've seen some on ebay for a couple hundred.
Screw it, Lets brew it
Primary 1- BM's Cream of three crops.
Primary 2- Paleface Scalper
Primary 3- Monks Reward (Kreuzberg)
Kegged - Honey Badger, Heady topper clone 1, Indian Paleface Scalper
Bottled- Skeptical Dog winter Lager, Hell's Belgian, Old Dutch Hiefer Hefe,Aphlewein, Chocolate Thunder porter, Jacked up lantern