Doesn't your car buzz when the lights are left on?
Perhaps she just needs a hearing aid. Would be a shame to give up a perfectly good wife that just needs a minor repair...
But seriously folks...
If there is no way to retrain her, you may want to consider one of those "Battery Buddy" thingies that cuts out when voltage drops to a critical breakpoint.
An alpha-geek could wire up a timer, and some relays, such that the lights would automatically turn off, say 5 minutes after the ignition was cut, just like many modern cars do.
Spiral cell batteries, such as the Optima, are said to be immune from damage from a deep discharge.
1986 300E 5-Speed 240k mi.