I think there could be a way to do it... but it would be complex. You'd need to run a parallel circuit from a 12v ignition-backed fuse from the fuse box to the lights, which would allow the ignition current to power the lights all the time. Then you'd need a 4 way switch relay on the standard circuit so that it would 1) not notice that power is going to the rear lights when the ignition is on, and 2) cut the power from the parallel circuit when the headlights are turned on and 3) prevent shorting the lights through the ignition circuit when the lights are manually turned on. Even with all this, this is just following the logic of trying to trick the CANBUS system to believe everything is working normally. If, for example, circuit resistance is being monitored through CANBUS then it will most likely spew an error and might put the car in limp mode.
Personally, I'd learn to live without them.