I have personally never OC with a rifle before, and where it may be legal, it may be hard to justify as carrying for self-defense. I have heard that in the less rural areas, it has been done, especially while walking to hunting sites. Also with a rifle mount in the back window of trucks.
Just not seeing a rifle as a very tactical weapon in a spur of the moment self defense situation. Though I have to admit, I have not tried training with one, and with your training, maybe you could prove me wrong.