There's no need to remove any panels to remove the spark plug, if you go in from the bottom of the scooter on the left hand side, and you have just the right size ratchet wrench, just the right length extension, and you're a bit of a contortionist.
I think (although I'm not in the garage and I haven't measured them) that the wrench is 6" long, the extension is 4" long, and I'm using a standard spark plug socket.
Fortunately, the wrench kit I bought from Costco had exactly what I needed.