No, it will still be a 20c pack, and you would end up with 3000mah. Wiring them parallel is fine, but as you said, charge and balance them separately. EDF jet guys do this all the time due the space constraints on these small foamy jets. Just get a bunch of deans connectors and make a "Y" harness similar to an aileron servo harness that you can plug the batteries into. Just be sure you use female connectors on the batteries and on the single lead of the "y" harness, male connector goes on the parallel ends of the "Y" and on your ESC or rx