Yes I completely agree but no that's pretty much the best we can do. It's the same in most helis.
Actually this isn't completely true, as discussed previously on this thread, mounting the unit upside down will result in the aerials being much more vertical but may add some visual obstruction issues. I thought I would try the simple and likely worst case scenario first but I will invert it next time and see how that is.
In that case, the easiest option to improve GPS fix would simply be to put the existing GPS dongle on a short USB extender and mount it on the top end of the case between the two antennas
That would be a nice solution, and in fact if it was inverted then it could go on the other end which could be much neater if I design and print a new end cap to slide on and contain the dongle.
I'm actually surprised at how well the dongle worked with the aerial facing completely the wrong way and insulated by a battery!
I've flown again for 2 hours since and these additional logs show that it could see an average of 10 sats and no loss of GPS data for both flights.
I still might move the dongle as I'm just curious to tinker!