From the Imp side I've beaten it with a Jerry dual ISD (I can't remember if there was a Gozanti in there or not) with a full complement of swarm aces that I brought as a for-fun fleet. We played his minefields. I flew the ISDs like Assault Frigates, circling and daring the fighters to leave the bubble and Haven to get close enough to engage the ISDs.
It was an utter standoff: he couldn't get the fighters close enough to threaten the ISDs without dropping them into range of my return alpha strike. Which he could weather, but to do so would have to position GH close enough to be jumped by the ISDs. He was shuffling mines to try and push them under my ISDs, but couldn't afford to overextend and lose the VCXs as he relied on them for Yavaris relay.
For my part, my ISDs could each weather a round from his squadrons, but if I flew into them it would be two rounds that they were eating, which would mean I'd have to commit to engage his squadrons under cover of GH, which is a fool's errand.
The key to beating the fleet with squadrons--and it is not easy at all--is that you have to have a meaningful ship threat that can reliably kill Gallant Haven without relying on fighter cover to keep it alive. If you can threaten that, you can force him to choose to either bring the squadrons out from the umbrella or lose the umbrella. Not only that, but it requires considerable skill to pull this off as there are a LOT of moving parts that you have to get just right, or you're toast.