I still can't figure out what you are arguing though. Is it the checkpoints themselves? Because I dont' see how those are a violation of the 4th. Checkpoints like that are generally set up when police know there is a high degree of probability that motorists will be driving drunk.
Or is it that such a checkpont allows them to look into your car? If that is the case you dont have much of an argument either because it is simply your opinion that police use them to get a look in your car. An opinon that doesn't make much logical sense. They want to look in your car, so they use sobriety checkpoints to do it? Your argument would have to be that they care less about people driving drunk than the off chance of find some weed or something else illegal.
What I think I'm picking up from George, and he will correct me if I picking up the wrong stuff here

, is that he is arguing that the laws are written in order to give the police license to have a means to violate the 4th Amendment.
And he has made a pretty good argument for that.
I think I'm leaning more to your point of view here, however, that it is a stretch to assume that the law was written for the purpose of having a means to violate the 4th Amendment.
On the theory that any law can be intentionally or unintentionally manipulated or misinterpreted by the ignorant or corrupt, that in itself is not sufficient to assume intentional or organized malfeasance or overstepping one's intended authority.
I prefer to think that the intent of cell phone laws, drunk driving laws, requirements for driver's licenses, insurance, registration, etc. are all appropriate to promote the common welfare, and check points are a reasonable means of enforcement.
I don't think we can automatically assume that the check points are intended for the purpose of anything else. I can see how they also could be used for the purpose of having an excuse to look into people's cars,
though around here if they're looking for somebody specific, they don't usually conceal the fact that this is why they set up the checkpoints.