Well that was easy!
There was a sign by the highway that said “lane closed on bridge” (no, it didn’t say which), but I spied with my zoom lens and saw traffic in both lanes at the crest of the span. So I geared up, got on the expressway, and rode.
I maintained a speed of 35mph all the way (until traffic slowed down at the toll booth). No one was in the left lane, and the car behind me stayed there. I just don’t look to the right, and I was fine. The attendant at the booth didn’t ask any questions, and I rode on into St Ignace. (There was a lane closed, but it was going in the other direction.)
Yay!