A lot of work is being done on fault tolerant and distributed flight control.
Advanced Distributed Flight Control System Architecture with Prognosis for High Performance Fighter Aircraft...
We would have also done this by offloading the entire program to foreign companies but instead we took the long and painstaking path for developing capabilities.
Best possible explanation of low internal payload is that AMCA will work in collaboration with other stealthy UCAV. More emphasis is being placed on sensors and range.