Ever thought of M'Chassis?
Now I just go to the track with 2 x 4200mAH Lipo packs, and easily gets 2 x >35 minutes of solid bashing sessions.
I don't even need to bring my charger along, though I do...
On and off I do bash with nitros, but they usually have their engine died before I dump my battery.
Australia has a very good Mini thread:
M03/M05's - The Aussie Mini Racing thread
Now sure where about was that, but the infos was top notch!!