i know theres alot of people that use two fuel tank in unison to each other, like having the stock one. than say having a 50 or 75cc hidden somewhere out of the way so they work together. i think that will solve your problem and deal with the clearance and space issue. I'm sure you can find a 50 or 75cc tank to tuck away somewhere.
just check the site on how to set up the 2 fuel tank system and your golden. was thinking about doing this for bash in sessions with my revo but never got around to it