Trimming canvas at outside gunnel seat location

[canoenut]

Looking for ideas on how to best trim canvas at gunnel seat area after finish paint. I could use a sharp utility knife, but I'm concerned that it might end up being a hack job.
Thanks,
Lowell

 

[Woodpile]

A sharp utility knife works fine, the trick is keeping it sharp, silica based canvas fillers tend to dull them up pretty quick.