Thanks guys, for your help/thoughts!
I felt I knew, what was needed to accomplish this simple shutoff. I feel that it can't hurt to get other's opinions, that likely know more than me.
So, went out, got er did this am. Cut the red, tied in the switch, drilled small hole into cabinet next to unit. Then fastened in switch, which shows on/off. Turned shore power on, reconnected battery power, went inside, switch to on, all is well. Listened to a Shania CD (Still the one). Unit plays up to 7 speakers inside, and 2 outside. All factory speakers have a great sound! :)
Close cabinet door, switch is out of sight.
Jerry