Great right up and pictures. all the Macgyverisms you used for the install are entertaining.
( the nail in the straw) also admitting your items you overlooked is refreshing. This forum is a great way to find answers. I did when I installed a dual battery in my 2011 4R. I also used the ML-ACR. I agree with you about the big red switch. I still have not figured out where to install it on the dash. when you do come up with a solution please post it.
Thanks. I hope that admitting my mistakes will help other people in the same situation.
Here is what I am planning for the switch. First, I believe there is no OEM fit rocker switch (or even OEM look really) on the market that is SPDT. This would be the best solution.
So, my plan is to get a switch from Air On Board (AOB) that is a ON-OFF OEM fit switch that says battery link. I will then use a normally open (NO) 12V controlled relay and a 12V impulse SPDT relay in series with the AOB switch as the control signal. The input to the NO relay is the control wire (which I think is the red wire in my kit). The impulse relay will connect to the black wire on one side and the orange wire on the other. The AOB switch will have one side connected to the 12V supply, and the other side as the control line of both relays.
Now, when the AOB switch is off, you get automatic mode from the ML-ACR. When you press the button, depending on the state of the impluse relay you will either force connect or force disconnect the batteries. I will wire the independent LED on the switch to the yellow and orange wire to indicate the status.
The trick here is that there is only one positive voltage supply to the switch, if I understand things correctly. However, I think the orange wire is always at battery or alternator voltage and the LED flashes happen by connecting/disconnecting ground inside the ML-ACR circuitry, so all should be happy.
Now to find some time to research the particular parts, order them, and wire it all up.