I would like to suggest:
1) in backend set up defaut cover (if user didn't chise one during registration).
2) keep on site 2 default avatars and 2 default covers based on Genre.

So if user didnt uploaded avatar, we still can know is he a male or femail just looking on his/her avatar.

Also pre uploaded covers would be good (like avatars).

Thanks.

P.S: JomSocial allready use it for example.