This negative feature of the open differential can be solved by means of a differential lock. They allow the driver to lock an axle differential by hand in difficult terrain, so that the output axles (the wheels) are rigidly coupled to each other. Curve turns are more difficult now, but a progress on any surface is assured.
RAW Offroad-Transporter GmbH is able to retrofit your Sprinter, whether it is a four-wheel drive or rear-wheel drive, with a differential lock with a 100% locking effect. The rear differential can then be locked in the cockpit at the push of a button. Now the driving force is rigidly distributed 50% to the right and 50% to the left rear wheel. Should a bike lose grip, it will only get max. 50% of the total driving force. As can be seen in the sketch here, it then ensures the propulsion.