Never ran the Kubota on any trail, not what we bought it for in the first place. I have a spray rig in the bed and it totes my inverter generator so I can power 110 volt tools when working around the farm.
Far as seatbelts are concerned, the Kubota has an interlock on the belts and it won't start unless the belts are secured. When I'm using it to spray with, I put the seatbelt behind the seat and lock it in, that defeats the interlock.
Like I said, didn't buy it for 'recreation' at all. Bought it for use around the farm, mainly for spraying. My buddy has a Polaris Ranger or some such and it goes like a raped ape and he does the trail thing. We don't and not interested anyway. I do on occasion run it up town to fetch the odd can of mower gas and I was cognizant of that when we bought it and why we didn't buy a diesel Kubota as top speed on the diesel is about 22 mph, whereas the top speed on the gas Kubota we own is 50. I don't want to impede traffic going up town at 22 mph. Around here, you can operate a sxs on the shoulder of a paved road and in town, they are allowed as well. Most town dwellers around here have golf carts, even my renters have one but they don't interest me as they are even slower and I'm not into charging anything electric in the first place, except for starting batteries maybe.