Step by Step

A copyediting colleague recently wondered if the following needed commas: "Starting as a laborer to painter to blaster to foreman to finally becoming a boss.” There are two phrases with some nouns in between them, so the problem is not just commas; the sentence lacks parallel structure. How would I solve it? "He started as a laborer, then became a painter, a blaster, a foreman, and finally a boss." In this way, I use just nouns to show both progression and the importance of the final role.