Maximising chance of glider Class D zone crossing.
As a cross-country glider pilot it is becoming increasingly difficult, in some areas, to conduct long-distance flights whilst avoiding all class D airspace. Which of the following are most likely to get me/improve my chances of getting a zone clearance? My glider is equipped with radio but not a transponder at present. I have a FRTO licence.
Call for clearance 5min / 5 miles before boundary.
Fitting a Mode S transponder.
Submitting a VFR flight plan prior to take off.
'Phone call prior to take off.
Any other suggestions?
P.S.: I don't want to loiter in your zone - I'm aiming to complete my task as fast as I can - but I may need to stop at some point to gain height - particularly when flying into wind.