Garmp1 - we are very much alike in our camping preferences. My family and I totally enjoyed Lake Itasca, walking across the Mississippi Headwaters on the rocks, touring the lake in a boat, spending time in the nature center and participating with rangers on nature walks and nature lectures. Great drive through the "winderness" on the one-way loop. You can rent bicycles and ride around also if you wish (we didn't do that).
You'll be coming up out of Iowa. You could spend your first night at the Helmer Myre Big Island State Park just South of Albert Lea, MN. We always camp in the White Fox campground but we like big sites with some isolation. The Big Island campground could work for your Class B but would be snug for our MH. That will be a 3 hr drive.
In the morning, head up to the Kathio State Park. Again, nice sites, not far from Mille Lacs Lake, interesting historical exhibits (I enjoy native american history), and fun places to eat. Hiking trail all over (hike to the fire tower) and well maintained. That will be about a 3 hr drive from Big Island. This would be a good one or two day camp.
Itasca State Park is another 3 hours away. You can easily spend a couple of days here. Take a side trip up to Bemidji and say hello to Paul Bunyon and Babe, his blue ox.
Another three hours North and you'll be at Zipple Bay State Park. This is wilderness in comfort! See where that is on a map...very tip top of Minnesota. You'll be fine in your B. Nice sites, isolated, deep woods feeling, and sitting on the edge of the Lake of the Woods is a wonderful feeling. A day here relaxing would be well spent.
Come back via Hibbing MN (great exibits there, check the Soudan mine, the Big Fire museum, etc).
Jay Cooke State Park, South of Duluth could be another camping spot. Take a drive into Duluth/Superior. Train ride is great fun. I wish you'd have time to do the North Shore and visit state parks there (they are totally awesome).
The St Croix State Park is a favorite of ours also. Nice hiking along the river but the sits are a bit more open than you might like.
Come back along the Mississippi river and spend a night in Frontenac State Park high on the bluffs overlooking the river. Then continue on South. You'll have had a real nice opportunity to see various parts of Minnesota, very different terrain, and fun activities.
Holler if you have any questions; I hope you totally enjoy your trip to Minnesota!
(Bring DEET bug spray when you come. I have a refrigerator magnet my wife got me from a prior trip "up north". Big mosquito, napkin around his neck holding knife and fork in his hands, caption "Send more tourists, the last were delicious!")