if you can post a photo I would appreciate it. I plan on sewing a stove jack on mine as well.I put my jack in a few weeks ago and was able to get it pretty close to the peak. You want to make sure you don't have it on one of the corner seams. I picked which flat side I wanted the jack on and put it up as high as I could between two corner seams and centered on the seam running down the center of the flat side. So it only only overlapped that one seam.
Does that make sense? I can take a picture tonight if that helps.
Which brand Stove jack did you go with?