The only thing the area doesn't have is trout. Other than that what would you like to catch?
The Rum river is easily accessed and fished from shore, wading, or canoe. Smallmouth in every spot with rocks and deeper pool area. N. Pike, a few walleyes, suckers, carp. All the lakes at the beginning, Ogieche etc., are very shallow and in addition to the river fish have good panfish and L.M. Bass populations but get weedy and tough to get at as the season progresses. There are a lot of other lakes up the west side of Mille Lacs too. All have good panfish and L M Bass. You probably need to do some seriouse scouting to find good shore fishing spots though. You should be able to catch Bass on a fly rod year round at sunrise or sunset, panfish should be pretty willing too.
If you'd like some real excitement head to one of the bays or just about anywhere along the shore at Mille Lacs with an 8 to 10 wieght and some 6" or bigger flys and try for the Pike, Muskies or SM Bass. If you put that pattern together you'll have some world class memories.
Any way you look at it there's more water than one person could possibly sample in one summer. I hope you post a few times throughout your stay and report how it's going. I do get up that way once in a while for walleyes. If the timing worked I'd love to throw some flys with you.
Jim