Thank you for the detailed responses @Richard_Le_. This makes sense and would be a great interim solution for us, but I'm struggling to get the {DE: Field Name} expression to actually recognize the field I need to count the characters within.  I notice the field I want to count is not an auto popula...

Agreed, this would be a very valuable feature and save our marketing teams a significant amount of manual effort and planning in ensuring their content fits their templates at the onset.