Locate your ironman save on your computer. If it's on the cloud, there is a copy there : ..\Steam\userdata\your account\236850\remote\save games
2. Copy it on the "local" save game directory and edit the copy with a software (notepad++ may be very usefull)
3. On the first line you will found the three letters of the tag of your nation (BYZ for exemple)
4. Replace it with another : (FRA because the BBB is always around hehe)
5. Load the savegame. You will play like france (strange ?)
6. Save it, change again the nation on the new save
7. TADAM ! It's no more ironman but a regular save