Got it down!

That sweet spot on the far right corner was the spot I needed. Once I got there I had all day to use the cannons. Got it on the 3rd try after you showed the spot in your video! Almost did it without losing anybody but 3 out of 5 team members flew off the train after Nilrog went down, lol. Tovra the last boss was a cake walk- glad to get that one done.

Now I will head to Auchiduon and hopefully get my legendary rings going for my whole team.