Tried legit... no joy. So I 'cheated' my ass off in SRL, although i would prefer to think that I 'exploited a flaw in the game's mechanics'. I did only discover I could do this by accident: I was checking through my quests and found I was already on 51% and I'd only done SRL. I only had TLW equipped because I'd just got a 310 one from an engram in PvE the day before and had put it on to boost my light. I fully expect this to get patched before the next SRL. Kudos to anyone who did it the hard way.