From someone not in WCW 07 here are a few ideas.
-if we want more participation in wcw-- then require all posts within 72hrs of catch(or as soon as return home from out of country). But put WCW08 forum board to be private so that only registrants can view this. This takes away the fears that lurkers will flood the area. And people who like the intel (as I would) would be more than willing to join-- knowing that they wouldn't likely place top 3
-fishing is about fun, friends we meet, and challenging your own personal goals...I bet many will be more than happy to 'out' a bite if they know only the wcw kayak community can see this report. It also takes some of the luck out of it...as everyone will have the same intel/info and some people aren't better connected to a private pipeline of info.
-Start it either immediately after wcw07 or very soon thereafter. With YT bite heating up-- if there was a break and it didn't start until the fall (or offseason for many fisherman)-- less people would be willing to pay and sign up. Summer fishing in 08 needs to be included if you want a large group of people. (more people = more payout)
-Supplemental contests/giveaways will definitely keep more interest....maybe some smaller prizes for players after top 3-- top 10 get a WCW Beanie...11-20 get a t-shirt-- 21-30 get a box of crackers...

etc..
my 2 cents that may only be worth 1 cent.