Second, I let the tenant know I know their criminal history and tell them to leave.

It was a very long drive. 18 hours in total on the open road, I would sleep in my car along the way and live off of gas station food.

If you’re not already using similar software, I’d highly recommend exploring these options—they can save you a lot of headaches down the road.

For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

Every adult should be fully screened to ensure you aren't renting to a violent criminal, drug dealer, etc.

But wouldn't this be criminal not civil?

Think hard about your criminal background criteria.

However, if that effort fails, the local agent is equally liable – criminally and civilly – for any fees, fines, etc. associated with the property." 

How else would you know which one is the criminal?

Once you start processing the credit/criminal, the money is spent, and you can't get it back.