This can work in theory - you don't need system control to expand. The only examples of it actually happening since 3.3, however, I think have been in locked systems where conflicts are impossible.
In practice, 3.3 made it much harder, because you'd need the controlling faction to be in a conflict and under 12.5% influence, or there wouldn't be 75% spare influence in the system for you to use for expansion. You can no longer just lock the controller in a conflict elsewhere for a couple of weeks while you get the expansion.
Back-of-envelope, the juggling needed to expand without ever starting a control war would probably be easiest in a system with exactly four minor factions, and you'd probably need two control conflicts - one to let you get past the controller safely, and a separate one at a lower influence level to stop the coup when you got to 60%. The fourth faction you use as a buffer to store influence before the war starts, and take it out for yourself once the conflict is going.