Good work and I’m subscribing for your updates! Can you walk us through your progress? Specifically the two main red leads that come off your primary battery? The grey line coming off the True? The two red lines coming off your secondary battery? The two black lines coming off your secondary battery? And, the two light blue lines coming off your secondary battery?
The two "light blue" wires are not coming off the second battery, if you look closer. They are green with yellow or white stripe and they come off the relay that's used for getting an ignition switched ground. One of the green stripe wires will be used to switch ground to the dual voltmeter (which comes with the Tru battery isolator kit), the other is a spare.
There are two "heavy" red wires coming off 2nd or aux battery positive terminal. One connects that battery to the Tru "isolator charger", and the other is going to either the winch controller (looks about the right size conductor) or perhaps it's intending to go to the aux fuse block which, in the pic, remains unwired.
I've put all that stuff, and more, in recently, but although I've kept the wiring almost as neat as possible, you can't trace it well from a picture - there's too much of it and I'm still not done.