Randy,
My two cents, but keep an eye on your liability. There is a church down the road from me about a 1/4mi, and last summer one of it's members saw me out bushhogging in front of my house and stopped. He told me that the guy that used to do their field, had moved, and would I consider doing the cutting. I checked into what my exposure would be if I entered into that contract ( any exchange of service for money is a contract, written of not), and found that in the state of Georgia it was more than I wanted to bite off. I ended up cutting their field just for the fuel costs for two months until they found someone that does it for a living. Hopefully that guy has the proper insurance, licenses, etc.
Not sure what it's like in OK, but if you're working for this guy and damage a fence, or hit a barn, or run over his favorite cow, you're on the hook for the costs of repair or replacement! Could get sticky, depending on the neighbor.
Hope it works out.