Scott, we're in Missouri, which I believe is the only state where your lawn guy can put a mechanics lien on a property for non payment. We fall somewhere in between lawn guys and painters from a conversation I had with the DOL. I'm not saying put a lien on the property, but put it in your contract. Send me your email and I'll send our contract language. It clearly states we get paid the day the job is done.
Also, as far as not getting paid right away I haven't run into the problem too often, but when I do I send the invoice daily until it's paid.
Subject line day 2: Reminder for payment due.
Day 3: 2nd reminder for payment due.
With joist it's easy to resend daily.
Haven't run into anything beyond 3 days on the residential side.