How does the state enforce such a law? Have they removed my right to eject people from my property for whatever reason I see fit? I get allowing guns in vehicles on public property, schools, city buildings etc. But, telling a private property owner what they must allow on their property rubs me the wrong way. I have no issue with people keeping guns in their cars, but the principle is what bugs me. Don't tell me I can't boot someone off my land for any reason I see fit.
You need to consider...there is private property that others can only visit with your permission (your private home) and Private property that is open to the public for several reasons...like a store, a motel, a business.
If that store, motel, or business cannot restrict who enters or works on that property (try the Americans with Disabilities Act as well as other "non-discrimination" acts...why could those places restrict a fundimental right, especially when it concerns the visitor's own private property (his vehicle)?
Now, for your home, that is a different matter, you do not have to allow the visitor's vehicle on your property.
If you have a business that is open to the public, you have no private property rights...just try discriminate against a protected group and you will soon find out.