There will be many use cases where you want to use a table, but you also want to have a footer with subtotals, subsequent calculations, etc. An Invoice or Work Order is a perfect example of that. I’m working on a invoice template at the moment, which is how I ran into this issue.
My recommendation would be to allow a user to define the end row of a table region. Or, you can think of this as defining the start of the footer region. That way, when you modify data types for the table, it won’t mess up everything you’ve done in the footer.
Although this might be a significantly large effort, I still think it’s worth considering - especially early on. Otherwise, you’ve basically eliminated the possibility of using Strict data types if you want to use subtotals with labels below your table.
I would recommend using a color other than gray to highlight the portion of the worksheet that is your Table. In Excel, when rows have been filtered, the font color of the row number changes to Blue. You could do something like that, also … but I think it would be useful to have a visual of what portion of the worksheet is the relational database table.
To be even more innovative, perhaps you could allow a number of rows in a footer to be frozen, so that you could always see the totals.