If GEP is your first waypoint then FPL can be like:
GEP J21 … rest of FPL, no dep and arr airports inside FPL pls.
If I could say to alternative FPL posted after my sugestion:
DLH J21 GEP …
But here I want be careful because due Departure radar following, correct turn toward DLH can be problem, especially with rwy27. We can see clear sit on route via DLH but ATC then in case of airliners need put aircraft to N area of airport to do right turn to sit on J21 via DLH, this can be maybe not expected. So in case of departure from rwy21/03 it is mostly expected to use DLH for FPL, with rwy03 is expected left or right turn to sit at J21 over DLH. As I said, here departure radar service handle traffic flow so it is uppon their responsibility. With rwy27/09 I don’t expect use DLH but heading turn to sit exactly on J21 with specific course, closer to expected aircraft heading after departure turn. On other side, I don’t have nothing to this alternative, it is ok also.