I am able to do it with MK III shields and the zenith shield ability. I had mixed MK I weapons. The enemies came out in groups of 1 at the start, and when there are 2 left they come in groups of 4.
The last one has the groups of 8. That one is hard. Which is why I don't try to take it alone. I can do it, but it takes three full tries burning all the ability power I have. When it gets down to 1 I go defense till the zenith wear down the nenzul starbases, and after one or two are popped from them the tide turns enough to go offense again.
Also, I don't worry if one or two ally starbases fall if I am maintaining a good pace on attacking the enemy starbases. The reduced number of ally bases causes the two enemy factions to fight each other uninterrupted I find.