Change the immigration policy, by getting to the heart of the matter. Give them the opportunity in their home

The reason people come to America, is to seek a better life. We need to solve the issue of why they come here. Make any necessary agreements with Mexico, so co-ops of businesses could help people currently in the US start a business in Mexico where they would hire local workers. The co-ops could be related businesses For instance a tractor company, farm equipment, seed company could be a co-op. The number of these could numerous. The one caveat would be the companies would also be required to create the same number of jobs here as they do for the immigrants. Co-ops of businesses could also be given tax breaks
As far as the Agricultural workers, give them work visa's so they can come into the country legally and work in the fields. After the season they would return to their home country.