You're trying to make a decision without the necessary data. Can the house be rented and if so would the rent (less property managers fees) be sufficient to cover her mortgage, taxes and insurance? This is a vital piece of missing info. Does your friend want to be a landlord, it's not for everyone and the further you are from your property the riskier it is.
Has your fiend looked into refinancing? If she's paying more than 4.5% on her mortgage she should be looking into this.
Your friend should be speaking with an attorney, under no conditions should she attempt to negotiate with her lender with out one and this would be the best advice you could offer her.
Is $10-$15 enough $$ to make it worth destroying her Credit?
Isn't her current monthly payment about equal to what she will pay for renting a place?
Then some of the questions are obvious, and so are the answers.
Just like all of us; she has to live with some of her decisions. Or not.
A short sale will damage your friend's credit but 'destroy' may be too big a word. If she is current on the payments and continues to keep current until the home is sold the damage to her credit will be var less. Your credit score is damaged more so when you miss payments than when you short sell. She will lose the money she put into the home, yes, but she will be eligible to buy again in just two short years.
So, unless the rent would cover the mortgage payments and expenses, and unless she can find someone to help with maintenance and collection of rent, I would still think short selling would be a better option under the circumstances.