Well the cost would be minimal as you'd be doing it yourself. I've never seen one in an SV. It would need it too. I wouln't recommend one for 5" waves. The SV is a pond racer. Too fast for that kind of water at 27" long. I don't honestly think there is an affordable RTR that would run in those condidtions without frustration. Possibly the Villin EX? It's a good rough water boat and not quite as fast as the SV. And is upgadeable. (this one has been)

http://www.youtube.com/watch?v=psIbEpwo4Fw