Moi Heikki,
It's indeed tricky to backup BIMcloud because it doesn't have any sort of incremental backup feature. It's best to keep only the latest backup created with a script and then use a different solution to backup the files to another machine.
There is a hidden configuration option in BIMcloud where you can set it to create the backups without compression. This makes the files even larger but then you can utilize deduplication capable backup software to backup the files elsewhere and save a lot of space on the backup destination. Graphisoft can probably give details about the configuration option, but it's not publicly available on the web to my knowledge.
If BIMcloud is running on Windows Server, you can also use the built-in deduplication feature of Windows to save space on the BIMcloud server itself as well when the BIMcloud compression is turned off. This should make the actual space utilization comparable to the default compression.
