Producing concrete code for what Alan wants is not the issue here. HIS question was if his algorithm would work, the answer to which was YES, but it revealed the problem of this algorithm being applied directly (and naively) to data in EEPROM, which is a problem because EEPROM only has a limited write endurance. Your "sample code" all too lightly equally ignores that issue.

To use EEPROM responsively (so that your product is not a ticking time bomb, waiting to break down, and boy, I've seen examples of this!) requires that you approach it as a STORAGE DEVICE, NOT A MEMORY CHIP which must only be written to if a condition is met which indicates that otherwise the data might get lost; that you do all the real work on the data in RAM; and that you employ an appropriate algorithm to write to the EEPROM (walking write).

Alan seems to have past the stage of worrying about this by now because he has indicated that he will simply plough on and treat EEPROM as RAM, and write at least once every 7 minutes, which will wear out the guaranteed lifespan of the EEPROM in less than 1,5 year. Congrats, Alan! Good call. Don't look for alternatives, don't look for how to DO use EEPROM properly. Just blinkers on and straight ahead. If you're not doing this for a hobby, I sure am glad I'm not your customer.