As soon as I can find a good deal on mirrors, I will know definitively if it is possible to enable the mirrors without the dealer. At this point I'm 99% sure it is.
There is a bunch of vehicle configuration parameters in the BCM that tell all the systems what options your truck has. These values get set at the factory when they download a config file based on what was installed. There is only one official way to change these parameters after manufacturing. The way it is done is by updating your vehicle in Chrysler's system with the new option codes. Once that's done, the dealer can use their scan tool to download an updated config file from the Chrysler server and into your truck. The dealer can add certain option codes to the server (like backup cam and remote start) but corporate restricts them. The other option codes can only be added by someone in corporate (generally engineering). Sometimes they will do this if a dealer calls, but most times they will not. It all depends on who is on the other end of the phone.
However, there does exist ways to modify the config parameters directly through the diagnostic port without Chrysler intervention. I have personally done this on other Chrysler vehicles, and it looks like I should be able to with my truck as well. I just bought it and haven't installed any options yet that I can turn on, but I will soon. I should have a new RA2 radio here next week and then I'll try to turn on the backup cam.
I was able to successfully turn off and back on the auto headlights, and I do have access to config flags for power fold, autodim, signal, and puddle for the mirrors, so I think it is very, very promising.