9569, You bet your crazy but can you do it? probably should you do it? no.
1. your single axle probably doesn't have brakes.
2. The Kubota 4wd
L3400 weighs around 2600 with no FEL and no other attachments, fuel, oil etc so before you start your are loaded to max tire ability how about the axle is it a 3K,5k,7k or?
3. Have you checked with your state DOT laws most require or are about to require brakes and inspections. The ticket for pulling overloaded on a trailer without proper safety gear will cost you darn near as much as a new tandem wheel trailer with correct axles, brakes and tires for your intended load.
4. check your coupler and ball ratings as well a 1-7/8 ball will not cut it typically and the shank size probably ought to be at least an 1 inch or greater for the difference in price get the 2-5/16 ball with a 1-1/4 shank and you'll never have to worry about a ball failure you can just worry about everything else.
5. Thats an expensive roadside decoration your looking at when you blow your first tire 5 miles from home and your spare halfway to where your headed in the middle of nowhere with a tandem you can slow down take it real easy and limp into town if you have a tire go bad and then a spare failure as well.
Now on my last statement your thinking what are the chances well I've pulled a overloaded Boy Scout Trailer for my sons troop for 6 or 8 years in that time we've had a road tire and spare fail twice. Now imagine your pretty new Tractor sitting on that trailer disconnected from your truck sitting by the side of the road with you gone to get a new tire. Make sure and write down all your serial numbers because it was orange maybe not a great discription to give the officer.
I'm not trying to be a turd but trade your single axle for a tandem with brakes and a 2-5/16 coupler you won't be sorry and the difference should be less tham one ticket for driving overloaded with an implement hanging off the back of the tractor and trailer because you didn't want to make the trip twice.
Steve