Charging with 240 VAC with J1772 will be twice as fast. So if you already have the 240 VAC you can use the NEMA 14-50 cable from your Telsa and use the cheapest Tesla-Tap you can find, since you only need 12.5 amps at 240 VAC for 3,000 watts.
BTW, to use the Tesla Tap from a Tesla Wall...