ask them or their witness (I always have them bring one, and me too) to be a "Fluffer" or "Tweaker".
This is a great question. I recently worked with a woman whom I have know for several years, and had to think of a way to ask her to "Fluff" herself or allow me or my wife to. I have to admit it was a tad bit uncomfortable, but she was 28 also. Getting a senior to do something like this would be like setting fire to the Bible in my parts of the world. I have a general rule, that I don't do that type of photography, unless you have graduated high school and mommy and daddy's money ain't paying for the images!
new Canon 10D shot