During the Tumbleweed install process, is it possible to put /home in a separate partition?
Yes. Use the custom partitioner area to create a /home partition and it will use that as the main home directory. Make sure to make root bigger than 43GB (try 50 GB) as snapshots will eat that space very quickly, and can cause a lot of upgrade issues. There is a way to expand btrfs volumes, but it is a three layer process, and can be confusing to work through.