Soon swarms of otherwise unemployed busybodies will begin wandering the streets of Albuquerque, invading your privacy and asking nosy and intrusive questions that no one needs to know the answers to. If you are only interested in whether things are “Constitutional” or not, then go ahead and answer the ONLY question the census is Constitutionally allowed to ask: how many people live in your house. Everything else that is asked is unconstitutional, which is a fancy way of saying illegal. No matter what “laws” have been passed in the intervening centuries “authorizing” the questions.
If you have any dignity and self-respect, then you will probably not answer any questions at all. After all, when the Constitution “authorizes” something wrong, the Constitution is wrong and is a force forevil.
The excuses used to justify the census are all statist excuses. Like saying they need to know how many children they will be locking up in the indoctrination centers in the coming decade. Like wanting to know how much effort the wealth redistribution schemes will be in the next ten years; where the money will be stolen from and where the vote-buying bribes will be concentrated. Or, so they will know how to gerrymander districts to manipulate the vote for those who still participate in that rigged game.
There is no legitimate reason for a census, and no good reason to voluntarily cooperate. Especially for anyone who values liberty.
At the very least, maybe a good case of “situational delirium” would serve you well. For example:
“Yes, we are a family of 17 Antarctican immigrants who belong to the Jedi Order, and live with our pets whom we have married in three-and-a-half-way marriages. We have no clue whose children these are living among us. We have 3 bathrooms, but no indoor plumbing. Our electricity is provided by our tank of electric eels. Our house has 197 3/4 rooms if you count the 8 other spatial dimensions which are wrapped around us. …You’ve got a little string of 7th dimension on your elbow even now. Please don’t take it with you when you leave, since that is where my archaeopteryx sleeps. But, it’s time to bow to the carpet slugs now, so I must go. May you serve the picklewarts with gusto!”
You can probably think up better responses, but none is better than the one which trumps them all:ignore the census.