Hello,
thanks for your input. Using the balance charger as in your picture is a fine way to charge them safely. I also have one of these chargers here.
Concerning BMS, yes, using a quality one is safe, but as I already explained, as long as you do a constant monitor of your voltage during discharge (in radio operation), and as long as you charge them individually and monitors if there is any deviation in a cell, you can go without a BMS.
If there is no way for you to monitor the voltage during your activation, then I agree you better use a BMS to avoid destroying your batts in case of an unaware deep discharge.
In my radios (KX-3 & LNR LD-5 I see the voltage on the display all time).
I suggest to watch this as it is quite well explained:
https://www.youtube.com/watch/c3tUuiXXA1Y
73 de Ignacio