I'm not a big fan of water-ballasted boats because water is a relatively lousy ballast medium.
First of all, it isn't particularly dense, especially when compared to the same mass of lead. Second, most water-ballasted designs have the water ballast tanks relatively high up, making the ballast even less effective than it would be otherwise. This leads to the boat having a higher center of gravity than it would if it were properly designed with a lead or cast iron keel.
Third, some smaller boats that are water-ballasted, are exceptionally unstable if you forget to fill the water ballast tanks, and that can lead to disaster if you've forgotten to fill the tanks. There are a couple of cases of water ballasted MacGregors capsizing because the tanks weren't filled or weren't filled completely, and in at least one case led to some deaths.
Yes, I know water-ballast is used on a lot of high-end racing boats... but that is for a very different reason. It is used to allow the captain to shift ballast from one side of the boat to the other, essentially a replacement for human rail meat. These boats also have a rather large keel that provides the bulk of the stability for the boat, where the smaller, trailerable, water-ballast designs do not.
If shoal draft and high stability are important, get a trimaran or catamaran or a stub-keel with centerboard, rather than a water-ballasted design.
I also think it is a bit foolish to invite the ocean on-board when a better design would not require it.
