From memory when I looked at this for my old 05 element...
The front one is directly wired to a vehicle switched circuit. That same power line also powers a relay coil. That relay is used to send power to the back outlet.
So... if you want the front one on, you need to rewire it without the relay coil still in the circuit or it too will stay on and drain your battery.
If you just want the back one on, you can unplug the relay and put a jumper where the switched contacts are. In essence, simulating an always on relay.