I believe the various governments (local, state, and federal) have not only the right to know who is living in their jurisdictions, but a responsibility to everyone else to know.
No, I do not support using that cherry-picked data to gerrymander districts, to reduce funding for various projects, (after all, legal or not, those people DO live there and the state and local governments have to provide some types of services...schooling, police, fire, even road construction and increased maintenance due to more vehicles on the road) and reducing the funding to the various agencies hurts the legal residents as much or more than it will those the (R)'s want to ignore.
Want to reduce funding because of illegals? Remove the illegals. After all, that is a 100% federal job.