In 2011, we used a drive base very similar to what Scott has described. We then mounted a modified C-Base to the top. We had a nice surface to mount our electronics, and we were careful to leave them easy to reach.
http://www.chiefdelphi.com/media/photos/36120
It was the best, most reliable drive train we've had in 8 seasons, and if the game calls for it again, we'll certainly look at it again in the future. It was built in just a couple hours.
I don't know if this exact setup would work on a non-flat playing field.