The Green Mallard, I like it, sounds casual but with good food!

I'm going to disagree a little bit with DD and suggest you avoid a May trip. I think there is greater potential of running into Mr Blackfly that time of year and weather can be very unpredictable. But as DD said the fishing can be awesome IF you hit it right. You are going fishing right 8-)

June is good. Skeets will be a little tough but mostly at dark and in the morning during breakfast. You could always bring a screened tent if basecamping is the plan. It can also be colder than you might think so be prepared (I like down booties and knit hats for sleeping). Fishing is still very good with the walleyes really firing up in mid to late June before they go to offshore reefs.

AND.......don't forget the amount of daylight you will have in June or July. Stays light till late. That makes for long days. If your basecamping bring some friends or bring a book ;D