If he is taking the company truck home every night, than you are just asking for trouble. You know he is at the store with the truck. You wanted to own a business. Now it's time to make a business decision. Take the truck away and save YOUR business alot of trouble.
Not in the lawn business, but I had a guy like this working for me about ten years ago. One of the best workers I ever had. My company transferred him back to the main building. He was at home drunk with the music blaring. Neighbors call the cops. Cops show up and he tells them to gtf off the property while wielding a knife. My company tried to work with him while he missed work, while in jail. He straightens up but eventually comes into work with alcohol on his breath and gets canned. I visited him in the hospital and tried to talk some sense into him, while they were trying to dry him out. Last I knew of him he's still the same. I guess what I'm trying to say is that it's just a matter of time until HIS business creeps into YOUR business, literally. Your employee already has a child. If he doesn't care enough to change because of that, then he likely doesn't care enough to change because of you.