Yeah, it's perfect timing to resurrect this thread, the boating season in MN is about to start up again
The trick with avoiding fools on the water here is just that... avoid them. Almost any lake near the Minneapolis/St. Paul area has an overabundance of weekend boaters any hot day in the summer. These are the folks that get out 1-3 days a year, are lucky if their boat works right when they do, and have zero memory of safe boat operations year to year. Most of the lakes they're on aren't worth being on anyway.. they're polluted and overfished, and too shallow to dive in. The exception is Minnetonka, which has the worst overload of boaters anywere all summer long, but also is deep enough to have a couple shipwrecks. Fortunately it's patrolled heavily, and some of my friends are in the patrol.
Any problems I have with fools on the water are recorded, including time, date, registration, boat description, and driver description, location, and actions on my part and are given to the WP. Ideally I'll bring a camera, too. They may not be able to fine/arrest/whatever in each case, but they will go find them and ask them what they were doing, which usually helps correct the problem. Occasionally they seize a boat for various reasons too, which tends to deter some folks.
If you want to avoid idiots in MN on the water and see only skilled captains, have great fishing, and lots of natural beauty, Lake Superior should be your destination
Erik