2A is referring to the current rating, not the capacity. Almost all mid/large sized powerbanks (at least 4000mAh and up) will supply at least 2A
Capacity would depend on how much you are planning to fly at once. 4000mAh should give approximately one full recharge of 3 batteries.
I have a small USB solar panel from AliExpress I'll be using to recharge the batteries when I go camping, since I want to reserve my powerbank for recharging more important devices in that scenario. That could also be a viable alternative (or addition to) a powerbank for you.