I have never owned a Hydro so im just guessing, but you launch it just like you think you do.. (maybe a little deeper than normal)
It doesn't have to be very deep, it just seems that way.
Once your back tires on your rig are in the water you should be good.. depending on the angle of the launch ramp (or shore)

My daytona was wider than the trailer in the front as well (although not as bad as a hydro), it launced just fine, put the fenders about 2" below the water and the boat would float right off with no problems.  With the weight of the motor and pump in the back, the front floats very light