You know, you got me thinking, by talking about posting the land, etc. I might go for it being illegal to not allow workers to have guns in their car if they are not warned. However, if the employee and the employer agree ahead of time that no guns in the car is a condition of employment, then I don't see the state taking the power onto itself to prohibit such an agreement.
But my other point is that it makes more sense to be allowed to carry on school property, which is truly public property. I may not think the contents of a car are an extension of private property when that car intrudes on someone else's private property, but I sure do think it's an extension when it's on public property. I believe the couts have disagreed widely with me on this however.
It would be irony indeed if we end up in a situation where our cars are inviolate on private property belonging to another, but subject to search on public property.
Let's throw another monkey wrench into this mix. What about a business that's a really B-I-G corportation with LOTS of major stockholders and strong feelings on the issue? Say Disney makes this case (and they do) and all of their stockholders decide to bail. Is there a point where compromising your ideals makes better business sense? Then what? Talk about the sole proprietor. He owns say a hardware store in a medium sized community. He makes the same demand. His employees bail and make it an issue in the papers. The pro-gun elements put together an effective boycott. Now what? Stand firm and go out of business? You can BET that the competition will make statements to the effect of whatever way they can grab the business.