Hey Derek, how have you been? Have you looked at Victoria's "wakeskim" (I think is what it's called). The prop is 4'6" and the Oogle is 4'10" I believe that the large version of the wakeskim is 4'8". http://www.vicskim.com/Product/Boards/Wakeskim/Wakeskim.htm
You could also check out the Polyvac, it is manufactured in several different sizes, but you'd have to add a fin.
Alternatively, the folks from Walzer will be offering boards that might be better suited. They will have different lengths AND thicknesses. It might me possible to stay in the 4'6" length with a slightly thicker board. Give CASkimmer aka Sean Ward a shout and see when those Walzer's will be available.