Why would you want to use such a term as "Wetback" except to incite? Seems you got what you wanted. Why not just point out the obvious? "Illegal is Criminal." I'm really not a fan of politically correct, but I also see no need to use derogatory terms when the simple truth is so much more powerful.
Here's pictures of the rally in Des Moines, IA
http://www.citizensfortightborders.com/forums/viewtopic.php?t=20
The socialist workers party was there too.