Rooting android 7.1.1 December 2017 security update without bootloader unlock

Hello, I am trying to temp-root my Motorola DROID MAXX 2, and I can not unlock the bootloader. I want to temp root so I can overwrite the bootloader with my own, unlockable version. Does anyone know of a temp root that would work? I have already tried dirtycow, RockMyMoto, and PwnMyMoto.