The balancing is mandatory. And the easier way is to recharge and balance in 1 go, as the most chargers are equiped with a balancing port.

Also, the 7S pack as example is annyoing in that respect , most affordable chargers have a 6S limit.
It's easier and probably cheaper to use 4 4000 mAh 4S 25C packs, 2 in series to create an 8S (+/-30V) block and 2 of those in parallel. Creating an 8S 8000mAh battery.