Personally, there's no way I would do this assignment. I am a victim of sexual assault, and have severe Post-Traumatic Stress Disorder and am terrified of the opposite sex. I even insist that all of my doctor's be female, just to avoid being in a room alone with a man.
But even if this was not the case, I would still feel that it would be not only very unsafe, but it would compromise who I am, to be alone with someone I don't know, with one of us nude. I would take that F in a heartbeat.
If you do want to try and complete the assignment, and you are able to find someone willing to work with you, I really like the idea that someone suggested about getting a group of other students from your class together and all doing the assignment together in one place. What they said about there being safety in numbers, usually proves to be true.
Also, Envisionary, your ideas about a baby, or going to the morgue, I think those are both excellent and very unique and creative ideas. If it was me I would probably choose the morgue, because I'm generally very uncomfortable around others, as you said you tend to be as well. So looks like you do have some options, if you decide to go forward with the assignment. But if you decide to take a stand against this whole thing, and take this to the dean, or try and find other classmates to protest with, etc., well, it has to ultimately be your choice.
Just so you know, you have my full support either way, because I know you will do the right thing.