Let's try that again, accidently found a key that sends email when not
finished....

>  RE: 100 amp vs 200 amp 1315
>
About the only way you are going to push 120 amps, let alone 90, through
that system is to short the aux battery hot terminal and 1315 to ground.
And you are probably going to fry some wiring along the way before that.
And you don't want to dump that much juice into any battery all at oce, even
flat dead.
But if you feel better with the bigger 1315 go right ahead.