The Sync as a backup is an interesting idea. I wonder if you can set up a Sync table to feed off a Sync table. If you can, then you could contrive the timing of the Syncs at once per day to have say 7 backups and each would be a day delayed from the previous one. ie they would cascade
for example
11:00 pm copy from Sync Day 6 to Sync Day 7
12:00 pm copy from Sync Day 5 to Sync Day 6
1:00 am copy from Sync Day 4 to Sync Day 5
2:00 am copy from Sync Day 3 to Sync Day 4
3:00 am copy from Sync Day 2 to Sync Day 3
4:00 am copy from Sync Day 1 to Sync Day 2
5:00 am copy from Sync Day 0 (live app) to Sync Day 1