To make the category less rng based, would using a qr code of a mii with a super all time favorite available at the beginning be allowed?

MiiWii, as far as I know, the entire point of the run is to get lucky RNG to get a good time. That's why my All-Time Favorite is 11:42 and my Super All Time Favorite is 2:52:06. So, to answer your question, No, you cannot use QR Coded Miis at the beginning as the whole purpose of the category is to get Good RNG.

Maybe it’s different miis

QR codes are not allowed.