One column is not a limitation
Email design has one real constraint and about forty imaginary ones. Working inside the real one is where the good work is.
Plain text still beats your template
I ran the beautiful HTML version against a near-plain one for four months. The plain one won on every number I cared about.
The archive is the product
Most newsletters treat past issues as a backup. They are the only thing a new reader can judge you on before they hand over an address.