Everyone's familiar with the common steampunk tropes. Air Pirate, Engineer, Saloon Girl, etc. etc.
So what occupations and costumes can you think of that are outside the norm? Either speculative, or an actual costume you've photographed?
For the first, I would like to suggest an itinerant agricultural laborer. A Spalpeen, if you will.
Due to the nature of crop farming, extra workers were needed during the Spring ( plowing, planting ), and especially the Fall harvest. The day-to-day needs of animal care were done by the farmer and his family, so they didn't need help with that.
Someone that owned a steam traction engine was very busy during both seasons. But they had to do something different the rest of the year.
Itinerant laborers were desperately needed in the Fall, but during the rest of the year they were "free" to find other work. Or starve ( a very popular option ). So the spalpeen is not tied down to one location. This would give your character the excuse to be almost anywhere during the rest of the year, in the lower levels of society.
Farming was (and is) a very dangerous business. I can imagine someone having a specialized arm to harvest corn (maize) or other grain. Their task might be to harvest the outer 8' of a field, because a machine or animal powered harvester would trample down this part of the crop.