You could file to an NDB. Or you could find an old RNAV unit. Ok, the Instrument Flying Handbook says if you don't get specific departure instructions to proceed on course via the most direct route. If there is a victor airway over the field it's not an issue to file the airway as your first "fix." The question is how far can you go and I don't know. I've filed airways 10 or 15 miles from the airport. What you have to remember is ATC has to protect your airspace. If you file to an airway 100 miles away, ATC is going to have to protect half the state you're in. They're probably not going to be happy about that.