Milw. Wisc. has the best wrecks in thier area... The prime season for diving is mid. June to mid. Aug... The best vis is when the water is coldest... So for weather, vis and lake conditions on top... My choice would be late June for a good garantee for a decent dive... Expect vis to be 50 - 100 ft at 80 ft or deeper... Water temp below is usually 40-45 degrees.. My favs are Milw. Car Ferry,,, Prins Willem.. Both as you know have u tube videos posted...
Have Fun !