Control the borders
If the borders are controlled, the illegals are not exploited and the vineyards, farms and meat packers that hire them will have to pay a living wage and start to upgrade working conditions.
By allowing the illegals in and not building a wall and equipping law enforcement sufficiently, by your own analogy, is much like letting slaver ships still bring and unload slaves to the Carolinas.
Exploiters don't change unless punished severely or their supply is simply gone - I support both to end the exploitation and to preserve the economy.