If you have a decent external battery charger, you'll be surprised at how quickly they can charge. The Nitcore brand is pretty decent for chargers and inexpensive. If you get 2 married pairs of 4 batteries each, you can carry the spares with you if you need to charge during the day (in silicone boxes, mind you to make sure that you're carrying them safely) and I'd guess a few hours (certainly not all night) and your batteries will be happier. Best of luck, and you really do want them all charged up equally, for sure....
Anna