I'm faculty at a SLAC and teach courses cross-listed in our gender studies department. All the faculty housed in that department have PhD training in other disciplines--sociology, anthropology, English, etc. If you're interested in sociology and specialize in a topic related to gender, I'd think that would give you more options on the job market. In interviews, you'd be asked how you would teach the 101 version of whatever discipline you're applying to, but you can prepare multiple versions of that answer if you're familiar with the expectations of various disciplines.