Couldn't the aeronautical capabilities of an unpiloted aircraft have a significantly higher ceiling if the design doesn't need to accommodate for limiting g-forces on a human?
KrakenSDR would do a good job of this, they combine five RTLSDR into a coherent array. The top end of their tuning range is 1766 MHz which would include the 1575 MHz of the GPS L1 signal.
The little five antenna array can even attach on the roof of a car for a handy ground plane. Prob not a good idea to drive with it out there tho.