For what its worth, Its like this,
Think of the direction the water is being forced out of the jet nozzle, draw a line through the centerline of it... this (for the most part) your line of thrust.
OK so were does lift come from if we are trusting down? If you find the center of gravity and calculate were your moment of inertia and drag forces follow that line until the two meet this is a point of leverage that picks the bout out of the water. One of the more notable effects is pitch; witch gives air entrapment hulls their lift. This Pitch effect works off the center of water lift as a fulcrum between the CG and the nozzle thrust moment (not line) Think of putting a pipe in the nozzle and standing on it...that is the moment.
Bottom line. (Finally) You trade thrust for lift. So if we move the nozzle back we have just created a longer pipe and we do not have to work as hard for same pitch gains and the center of water lift has less weight being exerted on it (i.e. less boat in the water). Along with ease of the leverage forces comes a more efficient line of thrust for the given result in lift and MORE SPEED.
In regard to AS post you most likly have an entrapment hull (or close to one) and once you develop aero lift youre waiting the energy by shoving the ass end further in the water.
These are all trade off's what works on one boat may not work on another, you get too long a pump and you loose to much in internal friction (as well as having to cut a hole in the back of your garage) these theories are for you to experiment with the limit is your imagination (or $$$$ as in my case)
Good luck Hope to see you in Havasu on Memoreal day http://www.planetsmilies.com/smilies/cool/cool10.gif