its really pretty simple
i have used this technique, but 4000 lbs sounds like a lot of water.we used barrels on the deck. the real trick is in the math. The halyard is set to a height that will heal the boat just enough to get thru the bridge your working on. with this system i would not want to encounter any boat wakes as i went thur the exercise.. anyway the halyard length determines the heal so when the bags touch the water your good to go.