David,
I supose that your RAM memory starts at 0 address, as FLASH does. Standard code is not relocatable since it probably uses absolute jumps and calls.
All the systems I know that swap code memories enable a permanent section of code memory from where the cpu fetches at least the swapping instruction.
However, your approach might also work.
Can you give more details about the specific instructions that swap the memories?.

Regards,

Alfredo del Rio.