We only used one 4G modem at the time and went out and tested both the Optus and Telstra networks by swapping static IP SIM cards at the nearest main road near the remote landing site. The Optus network was best there, but didn’t really want to work under 50cm above the ground. Our aircraft was only 2kg and therefore only 25cm high. Didn’t look good.
Our last minute idea was to mount it on one of the main wing tips, and then only have one leg on one side of the aircraft, so when it landed it tipped to one side and so that on the other wing tip with the 4G antenna would be higher off the ground.