I cannot speak for the other Cameron researchers, but I don't think my John Hil(l)yard Cameron married Kate McIntyre. I think that Kate married a John HENRY Cameron in Muskoka on 10 Sept. 1881.
I believe my John Hilyard married Ida Widdafield before he married his first cousin Eva Maud(e) Harnden. They had a daughter together: Lea Viola Cameron, b. 10 Mar 1888, I think. They also had Margaret Maud Cameron who was born about 1890 in Michigan. Margaret married Alan Pepper.
I haven't found evidence of a divorce - so John and Ida may be (as you suggest) bigamists. I think Ida went on to marry again in 1897.
I live in Lindsay, Ontario nearby the village where John H. was born and spent a good part of his life (Cameron, Ontario). I have John's will and a few newspaper clippings about the Camerons if you need them. I am also happy to do local 'look-ups'.
John ended up running a store in the village where Archibald had started his General Store (which is still standing). He does not mention a living wife in his will.
Hope this helps. My email address is grisward at gmail dot com.