I've done some repairs of this sort before, I'm poor so I can't afford anything new. One trick that I used from high school shop was somethignlike you describes with wooden dowels. You drill holes spaced evenly throughout the board that are the same size as the dowel. You glue/expoxy/resin(orwhatever you are using) the dowels into place. After everything has dired got out some sandpapre and sand the dowels down so that the fair up nicely with the board. This adds alot of streagnth without changing the hydrodynamics of the boards. Good luck.

Fair Winds