Urrr, isn't it fairly easy?
They've already shown that they can get a bloke almost to the gold before it gets close to toppling. Just make everyone gets really far back, then the lightest person jumps out and fetches rocks from the nearby road (there are plenty). Pile these up in the drivers' cab to stabilise the coach. Then the light bloke gets back in, fetches the gold and they have enough weight now to get everyone and at least 90% of the gold out in shifts. Leave the rocks in the coach as they're not worth that much...
Biting the hand that feeds IT
