I solo fused and enhanced offerings all the time when I do that "good deeds" quest for the artifacts. Just stand on top of the big dome to the right and use it for cover. Shanks won't climb it, snipers can't hit you and it's very rare that the enemies will go behind it. I just dismantle the perfected offerings unless some passer buyers happen to join me. High impact scouts and snipers are your friend, friend.