That's a good idea for the board leash. Also, remember that if you're using something like the Cab IDS system, and you find yourself having to self rescue, you can always detach the leash and connect it onto the board, as the leash does not form part of the depower set up.
Then just throw it behind you and forget about it, I've done that before. It's not ideal, but if it's an emergency situation I would do it. You're still hooked in when winding up the lines, so you are still attached to the kite. In the event that you have to ditch the kite, at least you still have the board as a floatation device.
If you self rescue, I would then pull it in, and chuck it in the kite upside down, with the bar.
it comes down to practicing in shallow water so you can hold your ground but still experience the real effects of wind on your kite. I'm not opposed to leaving your lines un-wrapped and just getting up to your kite, although wrapping does keep things neat. Know the effects of your kite's safety system and what lines to hang onto so the kite stays in your control. Again, practice in shallow water!!!