Hi, first off I dont know if this is already been done in DA.
A while back another forum member said that he felt that the starbases were to easily destroyed (even fully upgraded). Having played GC II quite a lot I have to agree that they are too easily destroyed unless you leave a fleet on the same tile.
My suggestion is would it be possible to give Starbases a logistic value so they can become part of a 'static' fleet? This would improve the graphics, and add a balance value to protecting the Starbase.
Just an idea. (awesome game BTW!)