Ok, so Ive given this some thought and maybe the best way to deal with the starbases lack of range it reduce the phase jump lanes. Arent they are 40 degrees now? Why not reduce them to 25 degrees. That way you can park a starbase right in the way and they can not jump around it with out it shooting.
How about being able to deploy long range detectors for starbases within a grav well? Give a star base three to four of those scanners which can be placed anywhere in the grav well. Each scanner has an own range of action. Once an enemy comes into range of those scanners, a starbase can use it's long range weapons to attack anything in the range of the scanner. The scanner might be cloaked and can be detected by scouts. Once detected, it can be destroyed. Of course scanners would need to be researchable.
Youst my two cents