I think we are all getting close to saying the same thing. When the wind
is way aft the boards come right up - it is just a question of when to bring them up. I also have raced Tornados along with many decades of mono racing
and Stumbles observations of pulling the boards up in light winds and then ensuring they go back down a bit in heavier breezes seems consistent with normal practice. At low speeds skin friction drag is the most important part of the drag equation. You can reduce it by pulling up the boards (downwind). You often see Hobies racing
in light winds with one rudder
in the air.
My point about leeway is that it always increases the drag of the hull. What one wants to do is to find the sweet spot where the reduction in drag from retracting boards is greater than the increase in drag from leeway. When the hull slips sideways too much the drag will increase markedly and the boat
with some board down will produce less drag.
I guess the point I can't seem to get across is that there is no difference between bearing off 7 degrees more and having 7 degrees of leeway. The generation of apparent depends only on your boat's track and not your boat's heading. But the point is not worth worrying about or getting unfriendly over.
In reality I tend to pull my boards up at a broad reach and forget about them. On a beam reach I put them half down and they go fully down to windward. I really like to have the boards fully up downwind because we have lots of crab pots of the NSW coast. With our kick up rudders we can hit one of these hidden floats, pop up one rudder, curse the fisherman who doesn't put a pole on them, put the rudder back down and sail on. When I hit one with the board down I spent 20 minutes with getting it off the board. Not fun.
I have a trick to knowing when to put the boards down - if they are hard to move down (or up) - put or keep them down. If the board is generating lots of lift
it will be harder to push down or retract - that is its job so make it work
and keep it down. If they come up relatively easily to move then they weren't doing anything so they are just being pulled along and pulling them up will be faster and let you jump the fish
traps. As always, listen to your boat.