Don't get any smaller than an 18' deck.
My DK 35 with loader and 6' brush hog is a tight fit to get my trailer ramps up on an 18' trailer.
I would recommend a 10,000 LB, 18 or 20' dual axle trailer with brakes on both axles.
I've transported my Century 3045(no BH) on my 18' HD 7700 GVW car trailer a few times. It's OK for occasional use, but if I were to make a habit of it, I would get at least a 20' 10,000 GVW. I'd also consider a gooseneck/5th wheel if you have a pickup. We have a 3/4 ton Suburban and 1ton Dodge dually, I don't think I'd use a 1/2 ton based on my experience.
Curious what your final deal was with Kioti?
Pacesetter
This past spring,I sold my 16' 7000gvw trailer.The replacement trailer I bought is 18' 10000gvw. Both trailers have brakes on both axles(ct. st. law). I used my trailer today,I was loaded around 6000# all went great. I would recom. no less than a 18' trailer. The longer deck gives you the flexability to balance the load for proper tongue weight. I have found that an adjustment of only inches for/aft can make the difference of a safe and comf. trip or a disaster.The load cap. is a ditto. My first trailer had radial car tires,very inadequate,my new rig has 10pr trailer tires.Bigger is better.