Add Dual Batt on 86 gmc

[chamberedcoal]

Ive got a 86 Gmc sierra classic, basically everythings stock but anyways, i hit a deer screwed up my front end abouyt 6 months ago, perfect chance to add some stuff and customize. I would like to know how to make my current system a dual battery system. i am going to use all new wireing harnesses(painless wireing) fuse block all that. and i was wondering how to go about that since there is only one batt tray under the hood?

thanks