As long as we're preaching about safety, also consider a more healthier option.
Tractor deaths , including rollovers, cause about 130 deaths annually. Any guesses on what the 2nd leading cause of death in the U.S. is, that kills 300,000(!) Americans annually? Relatively, I wouldn't be too worried about the seatbelts.
But why risk it when it takes a matter of seconds to buckle the belt?