[updated:LAST EDITED ON 14-Feb-02 AT 04:13 PM (EST)]Go for the isolator you will not regret it. I've got one in my truck and it works perfectly. And the wiring your talking about will work just fine. I've got my secondary battery wired to a starter relay then to my main relay. I've got it set up so that all I have to do is flip a switch in the cab and my second batt is giving my main batt a jump start. Also i would go with just a regular switch so that if your alt gives out for what ever reason you have more battery power to get you home.