That would be a fun experiment. I'd like to see what the range of the P3 is with the modified antennas and a standard battery. Running 2 controllers like you suggest would perhaps estimate the actual/practical range of the controller. So, which is more important: the range of the vehicle or the range of the controller. Checking the range of the vehicle could also determine which is the primary limitation on range - controller/signal or battery. If 2 controllers were used, then why not leapfrog them - change over control from the first to the second controller until the battery runs out. However, that doesn't get us to how far from a controller the max range is. Working out how to get 2 RCs connected to one P3 simultaneously would be a real challenge - but interesting.Absolutely correct. But there is an excitement to get the range computed.
Fun will start later to see who can achieve it.