I would stick with a 16s battery, with each battery having its own 16s BMS. That gives you 8 batteries.
It would seem to me that your selection of BMS is much larger if you stay with 16s as opposed to say 32s or larger.
Yes, I would use a BMS. Think of it as the final authority on maximum charge. All other components such as solar charge controllers and AC-DC converters must understand how to properly charge a LiFePO4 battery.
With that many batteries, I would look into a battery balancer that keeps the voltage balanced between all 8 batteries.