The question kind of says it all: I want to set the radio access technology (RAT) via QUECTEL_BG96_CellularNetwork::set_access_technology_impl() and I have been unable to unravel the call chain to determine how I take either my instance of QUECTEL_BG96 or Network_Interface and set the RAT on the BG96.
To implement this behavior I needed to modify the BG96 class itself to set the RAT via the CellularNetwork.