Just to reiterate, a star-base without a support fleet is actually not much of a hindrance. Especially Vasari as it simply cannot threaten a massive fleet. My typical invasion fleet (2-3 Caps, 20-25 HC's, 6-8 Carriers-40/60 Fighter/Bomber, 10-15 Support/Healing Cruisers, 35+ LRF, 10-15 LF, 5 SF-if you have scouted mines) will roll even a fully upgraded Orky in a minute tops. Now, it can be a bit harder if someone has taken to make an effective support for the Orky ( Repair Bays and massed Missile Platforms with max Phase Missile upgrades) but even with all of that, my fleet outlined above should roll through that relatively easily if you have upgraded as well.
If you are trying to kill a starbase with a carrier only fleet, then stagger the launch of your strikecraft. If you ensure that at any given moment there are some flying in, attacking, flying out and circling back around you will make it such that either the autocast may not trigger or if it does it will only get maybe 1/3 of your SC. That strategy has worked pretty well for me, I never have too many issues with Phasic Trap.