I'll chime in as one of the hardcore Constitutionalists who never went and got the permit..
If it's an older cop (they're almost always more reasonable than a youngungho type) I tell them as a show of respect. It always seems to be appreciated. Young guy? Ehh, why stir him up needlessly, besides now that they've made it legal to conceal in an auto without permit here in CO, I'm legal either way.
Massad Ayoob did an article once and advised exiting the car and locking it, so one could be away from the gun if/when it was declared to an officer. Sounded like good advice, and also denies a Terry search, also nice. I had occassion to try this once and it did make for an interesting stop. Copchick pulled me over and I exited / locked it and the screaming began. I walked around the front of my vehicle and onto the sidewalk, and then to the rear. Being very careful to have both hands in plain sight I began to approach her while she was screaming for me to get back in the vehicle. I stopped in plain view and said "you pulled me over so must want to talk to me, here I am" and ignored her request to get back in the vehicle. After a couple rounds of this banter she instructed me to assume the position on her hood, which I did. She asked to search my vehicle and I replied that I had no authorization to allow her into it because it was my Wifes vehicle and not mine. She asked for my lic/reg/ins and I gave her my license and told her that the reg/ins was in the glovebox. She said I can't retrieve it but she would. I reiterated my lack of authorization to allow her entry to which she replied that now I was going to get tickets for no reg/ins. I said in my politest voice, why can't you just run the tag and verify that it comes back to xxx vehicle and xxx name (my wife)? She didn't like that but did anyway. So she finds some unpaid parking ticket on me, advises me that I'm under arrest but I can leave the vehicle parked where it is. So I says, perhaps this is a good time to declare my weapon to you? (What weapon?) I said the Glock on the front seat in plain view. (If I take it into custody it'll be a long time before it's return if at all).
I don't want you to take it into custody. (Fine then we'll just leave it where it is then). I don't think it'd be prudent to leave an unsecured weapon in plain view, it should be secured don't you think? (Well you can't get it and wont allow me to get it so just what the h*** are you supposing?) Well, you could call my Wife to come get the vehicle and take possession of the gun since she only lives another 4 blocks up the road...(Who do you think I am, your secretary?) No Mamm but you do have a phone, she is close, and I do think it's be the prudent thing to do, there being an unsecured weapon in the vehicle. (Not TFL printable) and she snatches up the phone and says I'll try one time only.
I think it went very well, considering. You guys think I handled this ok?
Wonder if Ayoob still feels the same today about the advice he gave in that article back then. The political climate has changed some since then. It did work though so Kudos Ayoob for that.