Guys,
Just thought I would throw this in - it might just help someone…
I had this issue way back and decided that the EEPROM storage for long-term use was too ‘iffy’ ;-)).
So - I designed my PCB to include a low-cost I2C FRAM (FerroElectric RAM) chip - works like a charm ;-)).
These chips are WAY longer-life than FLASH or anything else - being measured in the trillions of write cycles 
and come in many sizes…
Hope this is helpful to someone else ;-)).
BR
Graham