I go surfing all the time, and all I do is i open up the back to my softtop (unless the top is off) and put the passenger seat down, slide the board in from the back, and then put the seat up.. it pinches it between the seat and the sound bar, I then put the seat belt on the board... I do this all the time and i have had no problems... works great.. better then the surf rack idea, tried that and it was too much work... this also only takes about 30 seconds to mount in there :) btw I have a 7'8" board... I can take pics if you want me to.... Windsurf.. i dont know... I dont do that...
Hope that helps Kurt