I know if I'm about to get into a shit fight I am looking around for ANYONE handy to give me a hand. As i303 said, every officer is different. First thing get onto 911 and let them know what's going on. Second approach the officer and asshole from where the officer can easuly see you and from a distance, ask if he needed assistance. Personally I would, and have approached these situations with my hands out to the side, palms facing forward so that the officer can see you are not a threat, and take things as they come. The hands out to the side at 45 degrees to the body is pretty much a universal sign of meaning no harm.
That being said, if he tell you to get back in your truck I would do so and wait till his backup arrives. You then become a very valued witness!
I personally have called out to bystanders to lend a hand which they have done reasdily and was much appreciated.
As for the CCW issue, unless the shit really hits the fan it shouldn't be an issue, just don't go flashing it around (and this isn't for you aziator) and when things become under control, and you are asked to give a statement then might be the time to say "by the way........" This is not meant to be a written rule, just a suggestion, as EVERY incident a LEO comes across is different, as is every officer.
Hope this helps.