Mine was easy to tell when it was doing a regen because when I got mine there was no ULSD available in the area and it would smoke when it was doing a burn. (regen) We finally have ULSD in the area and it isn't noticeable anymore. If you do a lot of idleing you will have more active regen events than if you are pulling. One of the times mine did it at idle was after an hour and a half waiting to get unloaded at an oil rig. Another time was just after I left a rig after idleing for a long time. As far as am I sure it is doing a regen, yes, go around and stick your hand a couple of feet from the tip of the exhaust pipe, believe me, you will know. Also the tip of the exhaust on my C & C is the same as any other model of new Dodge truck. One single wall pipe 4" in dia. , don't know what Ford has, never saw one.
According to the Master Tech Reference Book, "During regeneration, the external temperature of the exhaust system can reach as high as approximately 600 degrees Fahrenheit (315. 6 C). "