2nd battery install in a GMT900 Suburban - TP2 option

I know what it's supposed to look like because a friend is the chief of police and he let me look under the hood of his Tahoe.

I also wanted the ability to isolate a battery to make sure I was never stuck in the backcountry somewhere with dead batteries. I also wanted something that was turnkey/automatic. I have to do nothing extra to protect/isolate the aux battery.

Seems pretty pointless to drop in a second battery and not be able to isolate one.