When you leave Lake Hudson ( I would not spend three days there unless you have something particular to do in the area) head for the western part of the state and cruise up the Lake Michigan shore. Best beaches in the state, and great state parks. Further north check out Sleeping Bear Dunes National Lakeshore. Traverse City and Petoskey areas have wineries, great eating, sightseeing, and of course beaches. Take M-119 north of Petoskey; the drive from Harbor Springs to Cross Village is one of the most scenic in the state. Do NOT do it in your MH, it's very winding and narrow.
Mackinac Island is nice, with fudge shops and other touristy souvenir stuff, along with plenty of history and natural beauty. You can ride a bike around the island--bring your own on the ferry, or rent on the island--or take a horse draw carriage. No motorized traffic is allowed on the island.
Cross the bridge into the UP for even more seclusion and nature. Sault Ste Marie has the shipping locks that 1000 foot long freighters pass through between Lake Superior and the lower Great Lakes. There are a couple of campgrounds right on the channel to the locks, with amazing views of the big freighters. You can even take a boat ride through the locks.
