I think a 30% tax is reasonable...
BUT, this must apply to all remittances anywhere, so they can’t, say, send the money to Canada, and then forward it to Mexico.
“...force Mexicans to hide and smuggle their money, sending them into the shadows of illegality...”
#################################
Hell, that’s where they are now...A huge number of them....
Apply it to all money transfers to Mexico, Central America and every nation that says it has the right to send us illegal immigrants.