I've never been through a DUI checkpoint so I cannot speak to how much of an inconvenience they may be. But is it really that much of a big deal to simply roll-down your window, show your license, let the officer make a cursory look-over of you, and then move-on? There's no need to be an asshat about it by sticking some dumb sign up on your window and showing your license.
If you're not intoxicated there's no reason to be afraid. If you've had a few drinks there's good reason for officers to be concerned to ensure you're within the legal limits.
If you're drunk, your ass needs to be off the road and into jail.
We don't need loopholes to get through these checkpoints, we need to fill them and make sure idiots aren't on the road and people shouldn't be trying to find ways around doing things that are being done in the name of public safety.
So, roll down your damn window, talk to the officer, and let him get a full impression of your ability to safely operate a vehicle. If the law steps out of the line and arrests a person who's not over the legal limit, then fine. Let's fight it.
But, Christ. I think in some cases we can give the police a touch of leeway.
That is your prerogative. I am of the opinion that allowing law enforcement to circumvent your rights under any circumstances leads to a slippery slope.
But what rights are they circumventing? DUI Checkpoints are legal and all the officers are doing is to see your DL and giving you a cursory enough look to see if you're intoxicated. Remember that driving is a privilege and not a right. (Though the notion of it being a "privilege" always struck me as uncomfortable wording. Like government (which we the people hire and are in charge of) is patting us on the head and doing us a favor. Certainly there's a better word for something we have the freedom to do under the right circumstances but it is not a "right" we're allowed under the Constitution or any other legal documents structuring our government and society.)
If you're not intoxicated, best and most common-case scenario is you're inconvenienced for a moment. "Ugh, I had to press the "express down" button for the window!" or, "Ugh, I had to turn this crank a few times!"
Worst-case scenario you're detained for a while longer while the police figure out the situation. But that cannot detain you for long without cause.
Worst-worst case scenario you get something of a "false-positive" in any DUI tests (either the FST or a street-side breathalyser) taken to lock-up where more-than-likely the more accurate tests will figure out your level of intoxication.
If there's no to little ground to hold you very long or push any serious charges you've been largely inconvenienced. Annoying, but still mostly harmless.
Worst-worst-worst case scenario. You get those few asshole cops who trump-up charges and railroad you. You sue, plea to get the charges lessened or dropped and maybe get local news stories about you that go viral.
Worst-worst-worst-worst case scenario. You're actually drunk and your ass shouldn't be driving anyway and you're rightfully put in jail. The system works.
But, more than likely you're just going to be slightly inconvenienced. Roll down your window, show the license and get on with your damn night. There's no need to be an asshat about things.