Hmm. I once took tatooine when the empire had 10 units, turbolasers, all the buildings, and a shield generator. I just brought in the speeders, killed the shields, then retreated before the enemy could build aa. if they started building aa, i retreated before it finished, which therefore caused them to not be built. I kept doing this to all the buildings and retreating after each one. And use bombing runs if necessary.
Obi-wan is next to invincible. I know pirates are weak, but i took on a full base of them with just Obi-Wan. Heal, and while healing is recharging, protect, which nullifies most damage.
While facing more difficult groups like the Empire, always use raids. It saves time from you having to land all your troops separately. I use Obi-wan, a group of MPTLs, and either one T4B and an infiltrator squad, or just two infiltrator squads. Obiwan heals, which takes care of the bacta tank need. I build 2 repair stations next to the MPTLs and T4Bs and if there are enough build pads i build a bacta for the infiltrators. MPTL spotter takes care of bombing runs, Obi wan soaks up damage, T4bs wipe out turrets and masses of infantry, and also soak damage, infiltrators take care of infantry and use the grenades to blow up buildings and stuff, and MPTLs take care of anything else. When i keep discovering new build pads, i just move my MPTLs up.