I'm gonna mount several 8x12 glossy crystal archive lightjets to 1/4" gator board for my kid's room. What's the easiest and nicest way to trim off the excess paper?

fwiw, here's what I've tried on samples of 3/4" gator board:
trimming with a sharp utility knife. it works but the edge isn't as perfect as I'd like.
running the knife trimmed board through the table saw. this reveals the base of the paper and looks a little sloppy but the board is smooth.

I'm not interested in having someone else do it or buying more $$ equipment.
I want to use gator board that I have laying around so don't try to talk me into using something else.