Instead of building a wall or fence on the USA-Mexico border just for security purposes, a solar array structure can be built that also provides electric power to the region and helps raise the standard of living.
I suspect that immigration restriction will become much more realistic in the US long term if it is part of a package that is popular in countries that are currently sources of immigration. I see little evidence that current US immigration policies have done much for the Mexican population as a whole. The benefits of mass immigration and policies like NAFTA have been restricted to a tiny, wealthy minority in Mexico. It really shouldn't be that unrealistic to get the Mexican people to accept a sane immigration policy. I'm glad to see others working along lines that might make that help happen.