Is it possible to allow the radio to be on without the engine running? Newly purchased and this is my only real complaint

 

yes. when turning the engine off with your foot off of the brake pedal press the start button twice in quick succession. When you want to shut the radio off press the button twice again (with your foot off of the brake pedal)

 

Press the start button without your foot on the pedals, this will give you ACC, a second press will give you ON, third press will turn everything off.

 

A MUCH easier method is, with the car running and in park, hold the shifter button in while you press the Start button to turn off the car. The car will enter ACC mode for a certain period of time, 10 - 15 mins I believe.

I'm surprised that the Reaper doesn't know of this...

 

What shifter button ??

 

I shut the car off with the car in Neutral or Reverse and the radio stays on. Once ignition is off, shift to Park.

 

Do you have to press a button on the shifter when you change from Park to Drive?

Yes, that button.

 

This also works and the ACC stays on, seemingly, forever. I didn't mention this trick because it, potentially, can run your battery down.