Yeah that don't look right.
Having said that the bike is a Kawasaki KLX 250 trail bike so only 138kg. Not a light bike for a motorhome rack though and certainly not that one I would think when you add in the distance from the centre of the rear axle and probably 40kg of Rack etc. Van will probably pull as good a wheelie as the bike! I could manage one on the back of mine I would think. Just not practical though.