Actually I wasn't going to go that fancy.
Accessories are going to be wired full time the second batt.
Then I was thinking of using the IGN to turn on the relay for charging the second batt.
I think the IGN is good because as you turn the key, the STARTER would have access to both batts for starting(good in winter). And of course when driving the ALT would charge both batts.
And when the key is off, the relay isolates the first batt and the second batt would be used to power the toys.
That's the plan.
BTW, I'm not sure the proper way to wire this up, but again my plan was to leave everything with the ALT and STARTER stock, and move the power leads of the toys from the first batt to the second batt. Add a new ground wire from the second batt to the chassis. And finally add a wire from the pos on the first batt through the relay to the pos on the second batt. That would make both batts parrallel to each other isolated/joined with the relay.
Being as it's my first duall Batt setup, I'm not sure if I'm missing anything in the plan or not?