As far as I know, exchanges don't accept stop-loss orders on spreads, right? Is there a broker that accepts in-house stop-loss orders, to be transmitted quickly to the exchange?
If you are talking about inter-month spreads in the same commodity, you can work spreads. If you are talking about intra-commodity spreads, then you are right exchanges won't accept them. But if you are a big enough customer you can definitely leave them working with a trading desk and the desk will execute the spread when it hits your price. 5yr