I mean, if you actually think about doing this, you’ll just have to test on board a cargo plane and check how the different signals behave.
I’m not sure how the antennas are placed and if the plane the cargo is on will have the strongest signal.
You would just have to test those assumptions.
An in regards to identifying the strongest signal:
Build a cheap receiver, doesn’t need to be fancy or have the expensive antennas:
Then you will quickly see what data you get and what data you don’t get.