With the difficulty to add lat/long in the epmp's with firmware 3.5 here is a template that will help you send the coordinates using cnMaestro
{"device_props": {"systemConfigTimezone": "GMT","systemDeviceLocLatitude": "${Latitude}","systemDeviceLocLongitude": "${Longitiude}","systemDeviceLocHeight": ""}}
Thanks for sharing a template for other to use.
What is the difficulty with adding lat/long to ePMP devices with firmware version 3.5? cnMaestro's device configuration page should allow you to set latitude/longitude on the device using the textbox fields. Is this not working as expected?