I live on Penghu Island and I have Sunrise BnB specializing in kitesurfing sports.
I am happy to answer your questions to clear your doubts about Penghu.
1. Penghu is a windy place, it blows almost everyday, sometimes over 30 knots. But it is rare over 40 knots.
The wind was stronger 10 years ago when it blew over 50 knot a few times a year. Not any more.
2. Here is a link of kite scene in Penghu, my facebook group site. https://www.facebook.com/groups/4067845 ... =bookmarks
3. The water is clean on Penghu Island. No problem at our launch spots
4. If you prefer flat spots, that might be a problem. Our main spot, Longmen Beach, is a wave spot. Flat water is possible only when wind is lighter and the tide is low.