"I'll grant that typing a space in the spacer column is not hard. "
Definitely an understatement! :)
I used a period.
Typing it in the first non-header row of a 150 row table. then dragging down to fill that period into all 149 rows took about 8 seconds.
That action also selected all of the cells in that column (except the one in row 1, a Header row).
Changing to the Text inspector and setting the text colour to white, matching the background, took a little longer, but the result was completed in well under a minute.
The window below the table shows the full text in the selected cell, C3.
"Is there a technique to Format a column so it's always visually empty?"
Sure. Put some text in the cell, then set the opacity of the text to 0 (zero), or change the colour of the text to match the colour of the background
"Alternatively, is there a technique to Format a column so its contents does not visually flow into the next column."
Yes. Content of a cell will flow only into adjacent column(s) on the side away from the side to which that content is aligned, and only into cell(s) that do not already contain text (or other content).
Placing text in the 'next' column or setting text in 'this' column to wrap when it meets the edge of 'this column' will prevent text from flowing into the 'next' column.
(Google Sheets has a Clip text wrapping option.)
Numbers is not Google Sheets, and Google Sheets is not Numbers.
Also true if you replace 'Google Sheets' or 'Numbers" with 'MSExcel'.
Each of these applications has its own feature set. The sets do overlap, but they have never been the same as either of the others.
Apple has, on occasion, added new features, similar to features in other applications, and some of these appear to have been sparked by user requests.
Should you wish to request the addition of a " Clip text wrapping option" to Numbers, you can do so by opening the Numbers menu (in Numbers), choosing Provide Numbers Feedback, then making a Feature Request.
Apple does read the Feedback, but will respond directly only if they require further information regarding your suggestion.
Regards,
Barry
