I'm most likely going to get slatted for saying this - but the easiest solution is to just not wear the belt...! :confused3:
I know in our modern age of health and safety, risk assessments etc.. that tractor manufacturers are now forced to fit belts, but personally I have never seen or heard of anyone who actually wears the belt while working in the field - although I do know a few farmers with fast tractors (over 25mph) who do wear seat belts on the road.
Most large tractors still have a safety decal in the cab, informing the operator to remain seated and hold the steering wheel in the event of turn over - as long as you do this (and of course have proper ROPS fitted), then you should be fine in the event of a roll over. If you really feel happier wearing your seat belt, then maybe get a seat which can be swivelled and locked at an angle (again standard in most large tractors) - this allows you to sit at 45 degrees (with your belt on if you want), and see both ways easily....
Of course it is totally your choice of whether or not to wear a seatbelt, and I respect that many people will not share my opinion that they are not necessary in the field.... :thumbsup: