Can a restaurant be "part-time kosher"?

Secular-raised Jew here – ashamed to say I’ve got little to no kashrut knowledge. I’m hoping someone can help me answer this:

I’m writing a screenplay which features a food truck that is owned and operated by a non-jew, but that is near a haredi neighborhood. I wanted to include the presence of a mashgiach in the storyline, that would come to the truck to supervise (light the stove, etc.) a few days a week, allowing the truck to have “kosher days”. Does this make any sense? I want to be culturally sensitive.

Of course if I get funding I’ll get more knowledgeable people onboard, but for now I just want this part of the story to stand.

Thanks!