MJeff,
I concur with the previous two comments. I am all-struck at the number of small boats that I see daily, that have had small towers added to their boats. Both center console and cruisers, with cabins, they are not designed or structurally sound enough to carry the weight of a human, that far above the center of gravity. Not to mention, that the decks, gunnels, of cabin tops that they are fastened to, are structurally sound enough, to take the stress of a bit of weight, way up in the air, in a seaway.
Take a moment and go to a marina that has some of these modified boats and you will note structural damage around the hard points.
The boat manufacturers would have to not only beef up the structure, to carry forces, imposed by the boat in a seaway, they would also have to conduct stability test, to ensure that the boat could perform as designed, with significant weight aloft. You will most likely not find any small boat manufacturer that with certify their boats to do this.