Freya already supports field-based properties. If you declare a property, but you don't provide an implementation, the compiler adds automatically a hidden field and implements the property using the new field. Even if the property is declared as read only, you can assign values to the hidden field using the property name, as long as your code is located inside the declaring class or inside another class nested in the declaring class.
I was declaring the hidden field as private, but I have realized that it's better to declare it as an internal field, so any class compiled inside the same assembly could access the field instead of the property. Of course, if the property is read only, any other class still can not write on the field. Another constraint has to do with virtual properties: if the property is declared as virtual, it's not safe to reference the field instead of the property.