i've seen a low mustang over here with a hitch & boat.
granted, the mustang has more torque..but i'm sure a jetski shouldnt be that hard of a strain on the tranny.
i throw papers with my celica. normal days this is just fine..but sunday papers tend to be huge. on any given sunday i pack realistically 1500lbs in my car and it pulls just fine (from a redlight, i can climb straight up onto a highrise with this).
if you can get the hitch on safely...i don't see how pulling a jetski should be any problem.