Personally, I like the bonus KCBS added money idea. It's worked well for IBCA. A carrot always works better than a stick and the discounted entry for KCBS members was a stick to the organizers. Only way that would work is if KCBS discounted event sanctioning fee based on number of KCBS member teams were competing. This would not be too difficult to implement, but teams would have to be identified by member number rather than names.
The hardest thing with added money though, would be how to determine which contests get the added money. Some events are full with waiting lists so a new team is not going to be able to get in to compete there. Some contests are going away because they can't get enough teams. You don't want to not reward successful contests just because they can't get new teams in the contest, while rewarding contests that aren't successfully attracting teams. I don't have an answer to this. IBCA does it by way of the regional "Pits" but I don't know how the added money contest is chosen from all the contests in that region.
In recruiting new contest cooks, I think it's organizers that do that by putting on local events. I know our local organizer was who first got me to cook a contest and I was hooked after that very first time. KCBS has a great membership recruiting plan with the CBJ program. One way or another there's got to be a way to recruit cooks as members too. I wish we knew how many of those 11,000 teams were members??? Is there a benefit for organizers to be members?