All states have an exemption for farm trucks, but you must be hauling farm products. A lot of troopers are as misinformed as people who make posts on forums. Have you read the Georgia DDS codes?
http://www.dds.ga.gov/commercial/Rules.aspx#2You are right, many are misinformed. I'm not though.
Recreational vehicles are exempt from CDL.
A class E license is for non commercial(i.e. No CDL) use. Farm use is not required. The link you posted is exemptions from a CDL, not how a Class E can be used. (below is pasted from dds website)
Class E (formerly Non-Commercial Class A)**
Truck trailer or tractor-semi trailer combination in which the combination weight exceeds 26,001 pounds and the unit being towed exceeds 10,000 pounds.
