Erasing and Writing typically doesn't play well with memory-mapped read.
The QSPI NOR's typically allow for relatively free-form writing, perhaps do with 4K pages/alignment.
I'd probably journal the writes across reasonably large sections, have the ability to recover the last, or perhaps use sequence numbers to data you ping-pong between two of the larger sectors (64K?). Do erase when it is more convenient, or resources run low.
