You can't solo VoG from start to finish at any light level. You'd have a hell of a time just opening the door trying to keep Praetorians off the control plates. Not to mention trying to kill Templar solo while holding the relic cleansing yourself and keeping enemies off you. Then there's the relics on the Gatekeeper, once you go in you'd never get out since there is no one outside to keep the portal open.