I probably could have finished it sooner, but I had never gotten the mountain before and was being super cautious.
Here are a few tips I learned in that battle:
You're best off sticking to two types of bots: Attackers and Healers.
Attackers should have 3 rocket launchers, 1 stunner, a mortar, the range module, and antigrav legs. Rockets do lots of damage and, with the range module, outrange most turrets so you can easily weaken them before charging in. The stunner is just awesome, as it completely disables both bots and turrets, preventing them from shooting you and making them get hit more.
Healers should have 4 repair beams, firewall module, and antigrav legs. No mortar, because they can't repair while firing it. Just leave that slot empty. Build one for every 3-4 attackers, and try to have at least one with every group.
You can use manual control to snipe the turrets around a base you want to attack, but you shouldn't destroy them completely because the enemy will just build a new one before you can cap. Weaken them instead, so they only have a little health left. Then send in your army. The first few volleys will take out the weakened turrets, letting your bots stun and kill the ones you couldn't reach. If you stand on the pad right away, you can turn the base neutral before any new turrets finish building.
Perhaps most importantly, the AI reacts slowly to your actions, and sometimes not at all. They can be hoarding a giant blob o' bots on the southern beach, and will happily let you capture every base between it and their factory. It also seems to prioritize large but distant battles over a pair of attackers sneaking into the factory. If both enemies are alive, make your move when they get distracted.
If you can get control of the mountain, try to capture and hold all of the micromodule bases. Modules are needed for just about everything, so they won't be able to build much if they run out. Make sure to defend them, though. I saw the AI make a desperate attack when they started to run low.