with no GPS i am not super familiar, as i normally file gps direct or get some sort of SID out of chicago, denver etc. but as long as you can identify the nearest fix on the airway its fine to enter the enroute phase at that point. so for example you are leaving KXYZ and the nearest fix on an airway in the direction of your departure is called NOWHRE on the V113 then to vor -ABC v115 to you destinations vor of DEF. i would file as this- KXYZ as the departure point. route - NOWHRE-V113-ABC-V115-DEF- Destination airport. however you would need to get a clearence via the ATC ifr clearance number. 18887668267. similar auto operation as the wx breif, but you get a guy on the phone after you say what state u are leaving. You do this holding short of the runway or while taxiing to your departure end, tell them how soon you will be ready and what runway you are using. they give you your typical IFR clearance, (altitude, cleared route, comm freq's etc.) but with a void time. example, "time now 2113 zulu, void time 2123 zulu, contact flight service/atc by 2128 with intentions.