UPDATE: I pulled off the wiper cover and tray and could access the bolt... But I couldn't get a wrench on it. If I had one of the flexible socket extensions, maybe. Instead, I removed the air cleaner assembly and then took out the intake bolts. This let me move the intake a couple inches (leaving the vacuum lines attached) which, combined with the removed wiper cover and tray, was enough to get a socket in there.
Took an hour to get to the bolt and 5 mins. to replace the coil and plug (old plug was fine). Reassembled, cleared the codes, test drove and all is good.
Thanks for the advice.