In case anyone stumbles across this post in the future wanting to do the same thing, it does indeed work. I ran the cables in parallel between the BMS and ESC, and 3d printed an xt60 mount that goes on the rear truck. Another thing I discovered it that you can just plug in the external battery and run the board off of it as long as you do not turn the power button on, but I would not reccomend it because if the cord gets disconnected you will lose your breaks.
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