"I proably would change it to super singles, and go with single rear wheels. But I will not be towing something with over a 4,000 pound pin weight, so the axle capacity with single tires only would need to be about 14,000 pounds to meet my needs. 7,000 pound rated tires are fairly easy to come by, and are not as expensive as buying 4 of the original size"...
There is a reason you don't see many commercial rigs running super singles....cost and limited availability....changing to wide wheels and tires is not for the faint of heart...with the limited miles driven by RV'ers, there would never be a payback to justify a change out.
"Trucks over 20,000 GVWR must stop at open scales' A RV is not required to stop"
Neither is my 32K pound registered "private truck", pulling my 5th wheel. I can't count the number of times I've blown by them in OR.
Just my real world experience, yours may differ.
I also agree on the questionable use of a farm tag...but ya never know 'til you try. I would think the insurance might be an issue with dual use.
Regards
Gemstone