I just checked the LDS catalog and the St. Edmond's, Stoco, film only covers about 1854 to 1858. Since I don't believe they were married until 1860, I didn't bother ordering it.
I found out that the only LDS records are for St. Michaels as you said, and I have just ordered 1298739, the film prior to the one you looked at. It will be several weeks before I get to see it (probably after Christmas). I will let you know if I find anything.
Meanwhile, I will also try to see what records I can find in Minnesota. One of the churches they attended in Minnesota burned in 1888, so I know there is a hole in the record.