Adam,
Sound reasonable to me.
Prodigy has a twin aerial setup, so suggest you take a look at how they are rigged.
I can't see it being a problem as the transmitter and receiver are on different frequencies provided the separation is sufficient. ( A long time ago I could have calculated it all ).
However, I have just read Reg's note and he has a point, although I suspect that this will not damage the radio as the distance is sufficient ( along with diff freqs ).
Otherwise you would be destroying your GPS every time you transmit.
I would checkout Prodigy.