Well, my trip to the library alerted me to a great new exhibit on Women Designers for the Stage, beginning with the original costumer for BABES IN TOYLAND and THE WIZARD OF OZ, Caroline Siedle, but I'm still not finding enough info on prostitution backstage and chorus girls' salaries in 1903. The best info comes from Irving Berlin's song, "How Do You Do It Mabel?" from 1911:
[1st verse:]
Mabel Brown came to town
All dress'd up in her gingham gown
And a ribbon in her hair
In her eyes a vacant stare
Joined a show, wrote her beau
Mabel wanted to let him know
She was earning, so to speak
Twenty dollars a week
Her beau came down to New York town
To see his Mabel dear
The minute that he saw her flat
He whispered in her ear
[chorus:]
How do you do it, Mabel, on twenty dollars a week?
Tell us how you are able on twenty dollars a week
A fancy flat and a diamond bar
Twenty hats and a motor car
Go right to it but how do you do it
On twenty dollars a week?
As Guy Bolton wrote in his bio: "Chorus girls get minks the way minks get minks."