I think in almost all states DUI applies to private roads accessible to the public, such as parking lots and driveways. Mythbusters drove drunk on a closed course in California and that was legal.

Only a few states absolutely forbid operating a motor vehicle while intoxicated (I know Washington is one). That said, you’d have to do something pretty absurd to attract the attention of law enforcement if you’re staying on your own land.

If they didn't want you to drink, John Deere wouldn't have put a cupholder on it. C'mon, that's entrapment!