I don't think this is a class where many G's, including yours, would do well.
If there's no speed limit and no RPM limit, the Farmalls with RD's will be cruizing at 12-20MPH, your 8MPH just won't cut it...
If there was an RPM limit or a speed limit, it would be a different story. With neither, it would be tough, and no, I don't think you need a scatter blanket at 20% RPM's, but the general theme is "open", so most will run it as hard as they can and you need to emphasize safety.
Not saying a JD can't be built to run that class, but it will take a lot more coin to get one to run and stay together than using the "Lego" method of putting a high HP, High RPM motor in like the other brands can do.