Only one technician in the back is all that’s required, he/she sets up the recording for the calibration run and communicates with ground navaid techs to get the desired settings on the ground equipment.
Wake turbulence is a possibility. Although if it’s any of the ILS components being checked, there can’t be any large pieces of metal between them and the transmitter thus precluding wake turbulence once the calibration run has been commenced.
Hell of a long way to ferry a DA62 just to calibrate half a dozen runways in the UAE. Interesting.