@Michelle140 I totally understand your dread, but who knows? This guest might be great.
One thing I would advise you to do is change your checkin times. Do you really want to be available at 1am to check someone in? My listing says 12 to 5 pm. That's the window I prefer, but of course I can make exceptions, but it's at my discretion, not the guest's. If someone told me they might check in anywhere between 6pm and 6am, I would reply that they need to narrow it down and check in according to my check in times.
I refuse to be a doormat...my house, my rules. Airbnb doesn't expect hosts to bend over backwards for guests...just to be fair.
Another thing I would suggest is to limit the number of nights a guest can stay in order to not be stuck with a guest that you don't like for such a long time. Especially since you will be sharing the space. I limit mine to 21 days, not only because I don't want guests developing tenancy rights, but because the short term stays are better if the guest is not so nice.
While the long term stays are enticing because of the money involved, you need to consider your peace of mind.
Let us know how it all turns out! Clare