I would've thought that teams running with the engines turned slightly down would give fairly representative data on cornering performance and overall balance without showing their hand, and while also conserving the engine, of course.
However, running certain fuel loads just to deceive seems highly improbable, as it would also give unrepresentative tyre wear data for everything they're trying to test, but I am not an engineer, so defer to anyone's superior knowledge on this.
Still, if there's a place to sandbag, Bahrain seems like a great place to find some and hide it in the sidepods.
