I ran Mantario trail solo from South to North on Oct 10th, 2020. It was a chilly morning (0°C), but it slightly warmed up in the afternoon. Most of the trail runs on the Canadian Shield which takes its toll on your legs. Therefore, I would definitely recommend having well-cushioned trail kicks. It was my first time on the trail, and I would suggest being smarter than me, and scout it out (if you can) before doing the whole thing, just to get an idea what you are dealing with.
Navigation could be tricky as well. I did take quite a few wrong turns, but I wouldn't go further than 100m without obvious trail, markers or stone structures. Whenever I felt like I was lost, I'd get my phone to get me back on track.
I had 3L of water at the start (I sweat a lot), and I ran out of it 25mi into the run. I stopped twice to get water from the lakes (1L each time). Of nutrition, I ran on maple syrup (it can't get more Canadian, eh? hah), Nutiva fat spread and lots of salt.
You go through wilderness zone, so prepare to encounter a lot of wildlife. I came across couple snakes and a bear. Be respectful and cautious. Remember, they live there, and we are just visiting.
Overall, I had a fantastic time. I'd highly recommend this trail - the views are mind-boggling. It's hard to believe there is such a beautiful trail right in the backyard of our province.