As I can see this technique isn't for everybody
, more of a suggestion for something you could try for it to be more comfortable for her, I use this method and have no issues rotating the body into position and I feel that it gives me much more control of the brush and is much more comfortable to use.
I can do both ways but 90% or more of my work is two handed. I will agree its a touch harder with smaller bodies but when working on larger bodies like touring cars no issues what so ever.