Please no (shoot them all)....(burn them all)...regardless of how you 'feel' try and come up with a WORKABLE solution.And there's the rub.
Absent the threat of deadly force, there IS no workable solution. An organized movement can overwhelm any LEO's through sheer numbers. And even non-lethal methods would be portrayed as racist brutality toward the "peaceful" migrants.
Unless our officials are willing to accept that these mobs offer the same threat level as a military invasion, all efforts to deter them will fail.
IMO.
carpet bomb the surface 10-miles into Mexico BEFORE they arrive. Not just roads, trails and by-ways. Everything. Make it a moon-scape so destitute that it cannot be traversed.
Tell Mexico to pay for the clean-up.