I spent many hours on 0903 GPS issues and nothing really worked. As you pointed out the main source of interference is the camera itself and no matter how far you place the GPS module from the main unit it won't make much difference.
I went as far as powering GPS from its own power supply but as soon as I connected DATA, the signal got drowned in noise.
I forgot to mention that I also copper foiled (like 95%) the inside of the camera and used shielded extension cable (audio cable - shield as ground and the other 2 wires for V+ and data).
In my case it helps. I played around with the distance and it makes a difference. The smaller the distance between the camera and the GPS base, the longer it take to lock the GPS signal.
Same result when I test the GPS signal strength with my phone using android GPS test.