Need some advice guys

[pipeous]

You could contact the race director for the event and discuss pitting options. Maybe you could just do one stop with a battery swap at halfway in lieu of fuel stops? I don't think anyone would object and it widens your choices.

"Electric Monster Truck conforming to the rules of this class will be allowed to participate. That means they must meet the minimum weight. Electric trucks must make pit stops during mains. The appropriate number to be determined at each event which will be equal to the majority of the stops required by the nitro powered truck."

Again it is worth contacting the director about the 5s issue with your truck. I can't speak for him but
"1. All Standard MT's will run in the same class. Big block/small block is no longer an issue, larger displacement engines have a heavier minimum weight to compensate.
2. If a truck is modified so it does not fit these rules it must run in the Arena Truck Class. The RC Pro official will make the final decision."

as long as you state your case to show a fair compromise to running with the nitros, then you can work with it.