Here's the fix I used. Seems to work well.

Partly joking of course. Partly.

Personally, I think I'd look to split the customers by database rather than try to put them all in one. You've hit the real issue that's going to be brutally...

Without using log shipping or replication or availability groups (all of which you've dismissed), I don't know of any way you can easily move only the data that has changed...

Microsoft documentation on Columnstore:

Columns that use any of the following data types cannot be included in a columnstore index:

• ntext, text, and image
• nvarchar(max), varchar(max),...