I think the answer is easy. We just give all illegal immigrants rights as Proto Citizens. They still have to pay some sort of taxes, but they don't get access to the benefits full citizens get, like, you know, social security, any potential UHC, nor a minimum wage. If they want to live here doing the godawful jobs no sane person wants to do for shit wages, why not let them as long as we codify them and strip them of any meaningful rights and power? I think many of the tangible problems of living in a modernized society of capitalism can be solved with a healthy, official caste system.