For mine I definitely recommend going as light as possible with ur wetty and match it with an under-shirt poly fleece rashy. (some may can them 'woollen' but if they bought the right brand they would know that 'polyfleece' is the best description).
This combo will cover for several mm's of extra uncomfortable neoprene.
For Perth last winter a 2/2 of neoprene & a polyfleece from West Suits gave me the warmest sessions ever.
AND - absolutely no wind chill when u strip off the top of ur wetty for ur apres kite chat session.
The poly fleece rashie gets my vote as THE ABSOLUTE BEST invention in aquatic sports of all kinds for years. The best thing since 'one pump'

And from having scoured the world for a replacement when West went down (temporarily) my research rates the West Suits polyfleece no.1 by a long way.