Just sailed my SO29.2 for the first time last week and it seems as if I have the same problem and same configuration of 180 block and clutch. I am considering a winch but on a separate query - (if the keel can be lifted by hand) how much difference does this relatively light and relatively small protrusion make when it is down. I certainly haven't noticed a great deal of difference to steerage when under motor!
We have the SO30i which has a similar lift keel idea though differing in detail. We spoke to a SO29 owner before buying. He said he rated himself as quite strong and could when all was clean lift the keel by hand, but quite heavy.
Our boat has a different lifting system, I suppose it could be hauled up by hand, but the rope goes conveniently past the cabin top winch and we always use that. Using the winch, it is easy and we are careful to be sensitive to any abnormal resistance. As the rope only comes in about 200 mm full down to full up, I thing a block and tackle to give 3 or for to 1 would be enough if you use big enough blocks to not have too much friction.
The light (at least when in the water) board is not required for stability and does not make a significant contribution to stability. It is really a centreboard, like in an off the beach dingy, which adds lateral resistance to help with upwind sailing, but not needed for downwind, when even off the beach boats will lift their centreboard to reduce drag. But I tend to agree, it does not provide a large addition to the lateral area on our size of boat.
On our 30i, the centre keel, which provides the ballast, seems quite effective upwind, certainly enough for steering when motoring. So far I have not had a chance to closely compare up wind performance with it up vs down. (The disadvantage of not regularly racing). But in theory, it should help. It would be interesting to hear from someone who regularly races. I think we are talking small differences, but small differences win races, and sailing a little higher shortens the distance if we do not loose too much speed.