Would “thieving wetbacks,” “Drug mules,” “Illiterate Criminals,” or unskilled layabouts,” work?
None are terms I’d use but why turn the word “migrant” into a derogatory euphemism?
The drive-bys are using "migrant" is it is NOT a derogatory euphemism. At least not yet. But give them time.
That's why I prefer "criminal alien." It describes these border jumpers perfectly. It is a criminal act to enter the US without an invitation and they are not natives, thus aliens.