I guess playing it at a "Hard" setting maybe tougher than I expected. I guess given that I have lost almost all my space battles but won the ground ones, the Rebels may have a tactical advantage on the ground while the Empire rule in space. I mean, if you are limited by a pop cap to 4 Frigates, how to take on 4 Star Destroyers?
I have adopted a "Raid" tactic where I send in 1x Artillery, 1x Tank and 1x Troop to raid and take over planets. Once that happens, the space station disappears.