Hi Mike,
When she was but a sprout, my wife used to play at the lights. When I was stationed at the St. Clair Flats Coast Guard Station on HARSENS Island, Michigan (67-71 and 74-76)I used to change the batteries and other light equipment at the St. Clair Flats Old Channel Lights. They look nothing like the current lights being offered by HL. Their version was from a much earlier time.
There is no good place to see them from land. There is an establishment called the Old Club at the Southern tip of Harsens Island that prevents you from getting very close. It's a private millionaire's club. Just outside of their gates, however, is a small traffic circle that affords a view from about a mile away. It's where I proposed to my wife. Otherwise, you'll need to rent a boat, and there are plenty of those places on Harsens Island. By the way, you have to take a ferry from Algonac to Harsens Island.
Good luck.
Rich