In a pinch, you can always fill that window arch with a large, opaque oriental paper fan or purchase temporary paper blinds (Home Depot) and fasten them into a sunburst shape, cutting to an exact fit the window. (they can be doubled, or lightly spray painted for more opacity.) They come with sticky tape, and push pins will do a great job of securing them too.
Shutters of that kind are a custom order- $$$ - and you will not be able to get them made and installed quickly.
I agree with CFrance on the plants. New landscaping will take time to arrange
and will require immediate and continual care, or your investment will be wasted.
It might be best to wait until you decide what you really want for long term, when YOU get to live here full time.
I would encourage the renters to feel it is allowable for them to purchase a pre-planted container or two for their enjoyment on the lanai.
Places such as Home Depot have them readily available and they are not outrageously priced. You might provide an inexpensive watering can!
A personal investment of $20-40 will encourage them to take care of the planters and they will get to choose what THEY like.
