that you need to do it in the middle of the school playground during the morning school run?
Now it's been a long time since I've done nappy changes on teenies (have had extended nappy use x 3 due to SN) but I really can't remember ever having to change their bums during the school run.
Granted I've had numerous poonami and poomaggeddon incidents with all 3 of mine but tbh that was a get home, strip off and under the shower job rather than a stop right where you are and change them scenario.
Baby in question wasn't even weaning age so wasn't stinky, certainly not hoiking judgy pants it was just a bit of an "eh? Really?" Odd things you see on the school run moment.
Prepared to be corrected that it was somehow completely necessary, of course. So please don't flay me alive 
Oh, and I know it's really small stuff and all but I've got a builder hosing a ceiling with sealant and with my asthma I'm not allowed in the room so mnetting for something to do whilst I wait...