Hey Mr Bacon sweet boat lets see some pics start a thread in pride and joy!!! Don't use the front bow sac at all. It weights the whole bow instead of just one side of the bow. If you need to lengthen the pocket I would have one person sit up there but it's gotta be waay to one side. If you have 400's in back and want to see how much difference a 750 would make, put both 400's on one side some day as an experiment. Remember you gotta sink the boat in the rear corner only.
If you have enough weight, you can sink the whole rear of the boat evenly, but then you've gotta add enough weight to one side on top of that to really sink the side and make the boat lean or list.