How to do a spark plug chop test without taking the whole bike apart?

['03KDX200]

I've been dialing in my jetting and spark plug heat range lately. I've got an RB carb for my '03 KDX 200. I know that the best way to confirm that my main jet is the correct size, is to do a full throttle chop test. Only problem is, I can't do this in my neighborhood. I need to do it out on a dirt road somewhere, so I don't want to have to remove the seat, fairings and gas tank just to get to the spark plug, like I usually do. Is there a special low-profile wrench that people use for this purpose? I tried buying a 21mm ratcheting wrench, but the open end doesn't have room to swing far enough to even line up with the nut on the plug, and the ratcheting end is too thick to go down over the plug. Not enough room between the plug and the surrounding metal of the cylinder head. Has someone found a way to do this?

[Tyl3r]

I thought I recalled using the closed end (12 point) of a 13/16's wrench for this without needing to disassemble the bike, have you tried that? Maybe I am not remembering correctly

[Owyhee1]

Motion Pro 08-0147/08-0291. Works perfect.

[SS109]

I use a standard 13/16" box end wrench without issue.