No “hands on” experience with the Solectrac ( though i do run a compact Iseiki on a small property).
If you really need a compact tractor for a “commercial farm” , as AW said, its intended use is important.
Like most EV manufacturers, i suspect that Solectracs quoted run times are on the “optomistic” side of reality, and the 3-6 hours will be a max possible.
The limitations of a 22kWh battery supporting a 18kW motor are unavoidable.
If you have to do much high load work,,tilling, mowing, chipping, or hauling,etc… you need to be sure that 3 hrs per day would be an acceptable utilisation !
To me , that would not be acceptable in a “commercial” situation.
You could also consider running a compact diesel on Biofuel ?