Hello, do you play MP on a dedicated, or a self hosted ?
What i known for the save file structur is:
-Chunkdata = i don't known
-Map_XXXX_XXXX = Contain the data of cells (players building, loots in crates etcetc)
-Map_t = stores the time like the in game date and other bits like the emergency broadcast system frequency.
-Map_p = stores the players datas
-zpop_xxx = store the zombie stats
If you are a local host, you can creat a script and run it as a planned task
wmic shadowcopy call create Volume=C:\
rem dont forget to setup the numbers of snapshot here HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Settings on a dword "MaxShadowCopies" 1 to 512
i planish it to run every 2h so if my game crash, i have lost max 2h of work.
And before i use this solution, i use a cheat mod to rebuild what was lost (building and loot spawn). It's hard and take a lote of time, bu still faster than 7 day of rework ^^