Good work on that.
Came to the same conclusion that the IBM-AES-implementation is too big to fit a usefule sketch in the 328
Is there a reason for not using progmem in libraries/lmic-v1.51/src/lmic/AES-128_V10.cpp? you commented out that one...
//static const unsigned char S_Table [16][16] PROGMEM = {
unsigned char S_Table [16][16] = {