I use a current windsurfing harness - those are very comparable to the before mentioned half harnesses. My sailing takes place mostly on local lakes - so there is a lot of tacking and in and out on the wire due to gusts. I also have an old bucket seat - I do not like it - it hurts!
When we hit to the gulf cost for a weekend and I sail in more consistent winds for extended periods of time I wish I had a full harness. Patrick