i Done it at lvl49 just use LoS (line of sight) around the pillars get clones to despawn using saber throw, from range and use basic strike/sunder armor/slash on clones one at a time as they walk around pillar for the main boss be patient when hes casting use moves like force stasis/force push + saber throw/
basicly run around pillars like a tool occasionaly hitting him and change pillar if he starts to cast an AoE ability near it
Done it on my 3rd attempt lvl49 with default T7 no upgrades for him atall (he dies right at start) Defense tree guardian - yes it was difficult - it should be end of class quest - is it doable - hell yes
no need to complain
And to the guy that said if you go total tank spec your screwed bs as i said before line of sight is everything he rarely uses melee attacks just dont stand toe to toe with him