Wiring Question (Aux. Battery and amps) W/Pic

Wiring Question (Equipment off of Aux. Battery) W/Pic

I'm looking into a second battery. I'm presently laying out how things are going to be wired. If
you look at the PIC, you'll see I want to have the carpc(computer), lcd, and both amps to be
powered off the auxillary battery. Each device has an ignition detection wire to be connected to
the ignition wire from the vehicle (same wire off a head unit that would start it up when you
turn the key).

The whole reason behind the alternate battery is because I want to be able to pretty much start
my vehicle up any time and not have to worry about a dead primary batter. Both batteries will be
seperated by a battery seperator of some type (I'm liking Surepower's units). The alternater
will be connected to the primary like it should and the battery seperator will control the
charging/seperation of the alternate. It will be a smart unit so I won't have to flip a switch
to go back and forth between the 2. I will however have a on/off switch to manually connect the
2 if I need some help starting the motor, winching, etc...

That's some backround info on the project. Bow back to my question. How could I integrate a
master override switch so that it would act as a positive ignition just for the devices
connected to the auxillary battery (items in the blue boxes)?
Scenario would be, I flip the switch and then take the key out and everything BUT the items in
the blue boxes would cut off. Then when I'm done listing to some tunes, I flip the switch and
the rest of the equipment turn off. A PRO to this would be the benefit of running the system
soley off the auxillary battery and not burning up the primary because it would not require me
to have the key in for the items to power up. When the key is in, there are other things that
are on and start draining the main battery.

Another scenario would be to just straight up get in the vehicle and flip the switch and the
(blue box) equipment would come on again, without the need for a key in the ignition.

Whew.... Lol. Sorry for the lengthy question. I just need to make sure you understand. Lol.
Picture: