The distinction is clear and irrelevant to this discussion. Keep in mind all kinds of clever schemes have been tried to circumvent the constitution. There is what's called discrimination on its face and discrimination as applied. Discrimination being the unlawful distiction we've been discussing. There is a plate full of cases that deal with residency or what's called prividges and immunities. Anything from milk production to awarding state or local contracts. All have failed in the same way your idea fails the test.
You use just enough tidbits to make one think you are a lawyer. Perhaps you are. I hope not.
If there is one thing about which we are not discussing, its discrimination -- per se or otherwise. Discrimination -- as the term is properly applied in a legal context --plays no role in this discussion at all. Now -- if states were only requiring proof of lawful residency from certain groups with immutable characteristics, then we would be discussing discrimination.
Mine is not a "scheme" to "circumvent" the Constitution. Frankly, the Constitution has already been circumvented by the weak and shameful reasoning of Plyler v. Dough. I don't dispute what the law is, I just agree with the writer that Plyler is ripe to be overturned, and is based on faulty principles. I also agree that the only way to address the problem is through the Court itself.