Hey, Eric, thanks for adding that comment to my thing about pres: you make an excellent point.

One thing that will help is to use a reflexion filter which protects against reflections coming from behind the mic, and then hang a quilt, heavy blanket, or polyester duvet ("doona" for you Aussies ) behind the singer.  I am guilty of recording vocals in control rooms, spare rooms, and other untreated spaces, but this makeshift remedy works pretty well.  (Obviously, the louder the singer the bigger the problem with reflections.)