We keep both a local snapshot (taken 4 times a day) and an offsite full image of our control server (well, all our Enhance servers). We have done disaster testing with restoration 2 times in the last 3 months. So far, that has worked well.
We don't utilize ProxMox, instead we use XCP-ng, but either will have good backup/restore options for entire VM.
My only concern is any database(s) utilized by Enhance itself. I could see that getting out of sync.
I will look into Kopia, it sounds like a good option.