Interesting idea, though is there a reason you're limiting this suggestion to cantrips? AFAIK in Pathfinder you can sneak attack with any attack-roll spell, leveled spells included.
Sneak Attack - The rogue's attack deals extra damage anytime her target would be denied a Dex bonus to AC or when the rogue flanks her target. [...] Ranged attacks can count as sneak attacks only if the target is within 30 feet.
I don't even think this rule is limited to Arcane Tricksters. Any Pathfinder rogue with access to spells can do this.
