@Matthew Konkel - I invest in a small college town of about 25,000. I rent by the room and do give 9 month leases. Honestly it gives me an advantage over others in town in typically require 12 month leases. I can charge more per month and it works out in the end. This allows me to a couple options over the summer.
If vacant I can make small repairs and updates.
I often get students who are looking for summer housing if they have a job or something else which requires them to stay in town (especially those who live in college housing and are forced out in the summer)
I will sometimes get students who decide they don’t want to take the time to move their stuff out so they will just pay rent over the summer and not even use the property just so they can keep their stuff in their room.
It provides me the opportunity to suggest a 2 year lease with the option to move out and not pay rent for the summer months. I have got several students who view this as a good deal.
In the end it is a little more work but it does get me in my properties more often to maintain them and allows me more options to increase my rental income over what would be the norm for my area.
Good luck to you!