Hm. How about using this for an ESC?
https://www.unitedhobbies.com/UNITED...idProduct=4691
Not that you'd need 100A at 12S, but the price is right. :) Should be a pretty cool build. A 20XL with that kind of voltage should just give you oodles of runtime.
Man, oodles is the coolest word ever, except for maybe weasel. :)
Sleeb