Working on my first IoT project for an off-grid trail running event that will require RFID detections for a period exceeding 24 hours. I’m looking for ways of extending the battery life (as everything needs to be battery-powered) and reducing the extreme heat generated by the M6E Nano at full power (for detections in a 8-10 feet range). How about adding an infrared motion detector to the PI Pico W that would switch the M6E Nano to full power when runners are detected and then return it to sleep mode after a given delay without motion? Otherwise, heatsink and a bigger battery would be my only other choice, I guess? 
Sure - this kit https://www.sparkfun.com/products/19516 combined with the sleep mode mentioned in the datasheet https://cdn.sparkfun.com/assets/4/e/5/5 … asheet.pdf should accomplish what you’re after
Have the PIR send an output to wake up the m6e, then after a read/write or whatever put it back to sleep until a new PIR detection occurs
Perfect, thank you. Just to confirm: the EKMC PIR requires 170 microamps (not milliamps) and 1 microamp for the EKMB, right?
Yep