First mistake is believing Trump will do any of that - or anything else he says today, as opposed to what he said yesterday.
Second, you’re not going to “throw out all existing politicians and start over” by nominating Trump.
Cruz can’t win the general. Trump can.
You at least have a rational reason for not backing Trump, I hope you're wrong because if you are right we are totally screwed. Trump full filling his promise on the border and immigration is our only hope of remaining a constitutional republic.