To come back to the original question : I only manage to take off with totally loaded up F4U-D (2x1k bomb, 8 rockets 100% fuel) when rolling back, full flaps and WEP.
NEVER managed it any other way. Is may be possible but no matter what I tried (trim, subtle rudder inputs, lifting tail early, whatever) doesn't seem to work. Some people may manage it though but I can't figure it out. So I'll take the long route... that works fine.