that looks great have you done a video yet? run time can be a problem because of the power needed to get a big weight up on the plane, playing with props can help a lot in both speed and duration, have you got access to any GPS equipment to get an idea of speed ? we found it was the only way to get a true reading, if you look around the net there are plenty of pictures of Huntsman 28s that you can look at until you find one you want to model it after it may be handy not to have to much in the way of fine fittings until finish playing with the set up,
But you have got it well out of the water , are you sharing batteries between motors or have they got there own packs if they haven't that will double your run time straight away plus will give you a bit more speed Boats of that size can take the weight if you watch where you put the weight.
Peter