These are good thoughts and good ideas. I like the idea of changing up how we assign the position of "Primary Photo" for each plant.
But I'll add: don't worry about the thumbs. My advice is to give those thumbs as often as you like without considering how it'll affect image placement. If it becomes an issue, then we'll find a smarter and better way to do that sorting. But it feels good to get thumbs, so give 'em.
