I am not into crawlers but I have read that ppl don't run nitro in them due to the braking and the clutch. It seems electric/brushless is the way to go.
The exhaust is it's own issue as well. Nitro exhaust is tuned for the engine, the reverberations within the pipes are tuned to match the engines and create performance. In a case like this, it really is a necessary 'evil'. It CAN be done and I see some very cool 1 off fun. The labor, the design...