I'm building a device to do some remote monitoring of power and temperature. I'm planning on using this with an Uno and powering the Uno with a 9V, 1500mA power supply. I have a 20000mAh LiPo to use with the shield. So here are my questions...
The Uno is 5V and so I shouldn't need to cut the logic trace. Correct?
If power is lost to the Uno, will the LiPo power the Uno until power is restored/in runs out? I want to send at minimum a 'Power lost' message.
You could cut the trace on the SIM7000 shield as described as described here, then use a 5V booster board like this one. You would then have to connect the LiPo battery connections on the booster board to VBAT and GND on the SIM7000 shield, as well as connect the 5V USB from the booster to the Arduino. With this method, it'd be best to use a higher-capacity LiPo battery to make sure it can handle both the Arduino and the SIM7000.