The Jato has a 'roof vent' that could be opened up for more air flow, too. I would recommend that around all cuts in the body you re-inforce the area with shoe goo, or goop. And try to round off the corners of your cuts. Corners are more prone to cracking than curves.

A good running, well tuned engine will run for many tanks without flaming out(shutting off).
Obviously that doesn't take into consideration running out of fuel from 'resting it's wheels' on it's roof. Also it's a tricky operation to refuel a running RC by yourself with the body on. When you run your engine with a pressure line from the exhaust to the tank to pressurize it, then open the lid to dump more fuel in, the resulting drop in fuel pressure is usually enough to kill an idling engine. If you have enough hands, you can blip the throttle to keep it running, while holding it still, while holding the tank lid open, while holding the fuel bottle...

Another thing to consider is the crank bearings. I know the older 2.5s were famous for leaky bearings, if you are still convinced of an air leak.