I avoid the Detroit crossing and use Sarnia instead.
The downfalls of Detroit include the Ambassador bridge, sometimes clogged with truck traffic, leaving only one lane for cars/rv's and getting to it on Huron Church is a pain while in a car, let alone when towing.
The Bluewater has three full lanes and while it may be a few miles/km's further it's not through metro Detroit and 402 goes right to the bridge. I haven't been on interstate 69 since Feb, so I'm not certain on construction but it's not traveled by as much traffic as the interstates around here.
Good luck