As BB said, no need to have the receiver antennae outside the fuselage.
If you fly with your transmitter antenna oriented vertically, then one antenna in the plane should also be vertical
With 2.4Ghz, the only thing you should not do, is fly with the transmitter antenna pointing at the plane, it does reduce range, you can prove it when doing a range test on the ground
Do you have the new SD-10G? One of my flying buddies has one, awesome radio. the RDS8000's have also been very solid performers at our field.
Good luck,
Pete