Kyle doesn't have to go head to head.. Lots of indirect options. He could shrink himself down like The Atom, or make himself totally intangible, phase into a floor or something, and pump out constructs from hiding... And with an AI, he has access to other tricks, like planetary level time manipulation tricks, freezes and stuff... Or a Thanos like stasis cube used on Blood in Thunder Thor, like one GL tried using on Doomsday, and only failed because of the plot device evolution.
A GL ring definately has enough firepower to deal with someone on Thors physical level, since Hal was using a ring to take out Superman and Martian Manhunter, and not the Parallax power. Kyle may not be Hal, but he's pretty good in the willpower department.. Contained Ultraman, that Superman clone, for a good long while, for one. Made a small moon once, too.