For storing 80kB or similar small amounts you may use external serial SPI EEPROM/FLASH (slow writing speeds, not critical for your application), or fast devices - SPI SRAM (ie. 23LCV1024 128kBytes, 8pin, needs backup battery) or serial SPI FRAM (ie. FM25V10, 256kBytes per chip, 8pin) or serial SPI MRAM (ie. MR25H40, 512kBytes per chip, 8pin) where FRAM and MRAM are nonvolatile.
See for example the newest from fat16lib RamDisk - a file system library for RAM devices like 23LCV1024 - Storage - Arduino Forum - you can even have the filesystem on the device today and it works.