Take a look at the SUP weed fin. Looks like a race board fin but swept back.
I use future fins sea sheppards on my Fish board. Very swept back and they go over kelp no problem at all. They go upwind very very well, but they may be a bit too foiled for race boards.
I also tried a surfboard with only two fins. Only 3 inches deep, but they ran along about 1/3rd or the board. It did not turn too well, but it went upwind like a charm. Something to try out.
Tarifa fin company makes a windsurf rave fin designed specifically for weeds.
If I am mistaken the find are screwed into the base so you should be able to change the base to use it in a Kiterace board.http://www.tarifafincompany.com/product_page.php?Item=Anti-weed%20Windsurf%20Fin&
Hope this helps