You don't even need to go through the step of getting CO status: NW Plat is recognized by COPA, as COPA's official frequent flyer program is OnePass, and as COPA and NW do codeshare. (It's kinda funny to see the NW name displayed curbsite at PTY). So, having said that, arriving about 1:45 should ensure you're through the Elite Line before the 1 hour cutoff. COPA also has online checkin that you can try, too.