reportion non citizens so an equal amount are counted in each district.
no district can be skewed to have too many non citizens: the reason: not doing that could be said to be 'voter supression' because the voters in the districts with more non-citizens have votes that are worth more than those in districts with less voters.
OR: don't count non citizens for the purposes of dividing up districts. They would still be counted in the census, but when they don't vote they would not be used for making legislative districts.
Radical idea? It takes away the incentive to pack districts with thrid-world people who have no idea that the 'free' stuff is actually enslaving them, and that the pepole giving them welfare are living the high-life as profiteers for the social service dot-org cabal.