"msturtz"......Your warning has some merit, but your explanation has some issues. If you disconnect the negative battery cable and do nothing else, there is NO WAY for the toad to get power to the computer. You could hook a hundred ground wires to the chassis, it's still not going to complete the connection (circuit) across the battery.
Here's what I think you're trying to say. If you disconnect the negative terminal on the battery and then INSTALL a 12 volt toad charging system, to charge the toad battery while driving, you could power up the toad inadvertently by back feeding through the connections. The problem is....you don't need a toad charging system if the battery is disconnected, it won't be drained by anything.
What you need is a connection from your coach to your braking system if it requires power, like a Brake Buddy or other brand. It needs to be connected separately to the coach, not via the toad battery.
