It looks like you got your answer. Put her in and enjoy. Even though I'm a Michigander now my boating season is NOT from Memorial to Labor (contrary to the Admiral's) I boat from the weekend around April 1 to a weekend or two B-4 Halloween (end-Oct).
This gives me 6 to 6-1/2 months of sailing
and sometimes I have to have a wind-breaker, sweater and gloves on, but hey the sailing is great. Last May 7th, 2010 I sailed Lake Michigan from Whitehall to South Haven (81nm) and although the marinas were still closed
(as to full service(gas, water etc)shore power is normally on by then) and there was ice on the deck in the early AM when we left Whitehall, the average temp during the trip was 35 deg.F and the sailing was great. Again this was in May so you never know in MI (on LM) because I also had great boating on April 15th with 60 deg.F weather.
Hey it's Lake Michigan weather changes quick, storms come and go, but it's fresh water and no sharks when you fall overboard.