So,
I've got a working framework for my project - a battery powered appliance that will occasionally trigger one of two solenoids, timestamping the operation and subsequently reporting them to a bluetooth connected phone.
I developed initially on a nRF52 DK (PCA10040 - nRF52832), putting together a heavily modified peripheral_uart sample with I2C and ADC support.
On the nRF52, when idling (Advertising only at a 2 second interval) I measured current consumption at 8 uA at the current measurement pins while supplying 3.0V at the External Supply pins..
I ported to a newly received nRF5340 DK with minimal changes (GPIO port assignments moved from gpio 0 to gpio 1). At the same idle state as the nRF52832 (the main loop is a k_sleep(K_FOREVER); statement), current consumption at P22 with power supplied at P21 at 3.0V from a regulated power supply) at about .37 mA.
I had to compile and load hci_rpmsg to get bluetooth connectivity - as delivered the nRF5340DK did not seem to have a network core.
Where do I go from here to get reasonable current consumption?