How difficult would it be to add a self-leveling platform to a vehicle like this ? I have seen open source self-leveling two wheeled platforms (segway without

How difficult would it be to add a self-leveling platform to a vehicle like this ? I have seen open source self-leveling two wheeled platforms (segway without the yoke) but I have not seen a self leveling platform on a 4-6 wheeled vehicle like this one ...