I know there are solutions to making emacs show the 80 line column, but I don\'t want that sort of visual disturbance. I\'d just like to make it highlight a line if it\'s ov
Another easy option is to run highlight-lines-matching-regexp on the expression .\{81\}.
highlight-lines-matching-regexp
.\{81\}
Every line with 81 characters or more will be highlighted with the color of your choice.