Didn’t come to think of that myself. Thanks for the idea.
I tried it actually. I partitioned about 50GB partition to SDXC card of 64GB. Formatted it to FAT32.
Camera accepted it and recorded on to it.
Windows shows it is of FAT32 and shows the recorded photos on the card.
But SFOS still said that the file format is incompatible.
However, even if SFOS would have been kind enough to accept this method, I would have been hesitant to really use it in practice. The thing is - even if the camera now accepted the card, I would not have taken the risk that it would have made some error later on due to non-standard formatting.