we used to run lots of smaller boats with 40eez pushing them , my 13 foot whaler with an old 40 would run a bit fast , but it was styrofoam and the motor was rebuilt a bit heavier than 40 , it still only ran around low 30 range and the other rigs ran in the range yours is running .
Sometimes a different prop will get ya a few extra mph , might try that ?
My suggestion is find a closer launch , that is what I would do for sure