Just tell her "no" since you like to feel comfortable in your own house and like to walk around naked, and that she may feel uncomfortable if she moves in having to look at you like this all day.
Also, if she is hot, tell her that your other friend is in town and he wants to stay at your place as well. Say that she can stay too for a day or two if she doesn't mind sharing a couch. This will eliminate her asking to stay at your house in the future as your friend will take over the responsibility and be grateful at the same time.
On a serious note, I had a good friend moving with me and my girlfriend for a "week until he finds a job". He didn't find one for the next 6 months while living in my living room. We are no longer friends. At some point he started to feel comfortable, empty my fridge on a regular basis and invite his girlfriend over all the time. I started to charge him half of the rent, to which he got mad since he "only was sleeping in the living room", we fought all the time and eventually he moved out on a bad note. I only spoke with him once since then and it's been a few years. Unless you don't mind her living there, don't do it. Its a lot easier to say no since your girlfriend is the only one you are willing to share the house with than deal with the consequences. If she has no other option, no money and you still want to be nice and help, rent some cheap motel for her as a present but make sure it doesn't make you look like you will do it every time she is in town.
r gtfo!
