Hello and welcome! Here are 3 different links to interesting Prius rear wheel skirt ideas.
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Possibly you've seen them before, but they seem like a good place to start. Saw you've got grille blocks and that's a great addition, sounds like you're off to a good start.
You might consider starting a fuel log here if it's something you'd be interested in updating. They make pretty graphs and it's fun to track your vehicle over time. For instance in
my fuel log for my retired Yaris, you can clearly see the beautiful bell curves my summer VS winter driving made.
Then again it might be too fiddly to have to punch in all that data so that's understandable too.
In any event, hope you have a good time here.