Sorry Wacky, Duffster is correct. A farmer is not required to have a CDL to operate a CMV. As long as he/she is hauling their own agricultural products or machinery, they can drive an 80,000 LB semi unit with just a class 'D' license. They also must comply with the other restrictions, such as the 150 miles limit from the farm. That's coming from a State Trooper with 20+ years.
Getting back to the original poster's (BoFuller) questions. I agree with most others here that the trucks you're looking at will require a CDL. I would suggest that if you have questions, contact the AZ Hwy Patrol. They can answer questions that you have as they are the ones that enforce them in your state.
This issue of whether a CDL is needed comes up on a regular basis. One thing nobody ever seems to suggest is actually getting a CDL. It's not like getting a Master's Degree. If you have it then you don't have to worry about whether you need one or not.....problem solved.