I know it is not possible to program the mc-Gateway, but I have a couple of problems that could cheaply, elegantly, and easily be solved if we could program the mc-Gateway, even in an extremely limited manner. I say the problem could be solved cheaply and elegantly because an alternative solution to the following problems would be to host an MQTT server on a Raspberry Pi and bridge some of (and perhaps compute and re-package) the messages to Losant.
Losant has a payload limit, and other services may also have similar types of message limits. If we could tell the mc-Gateway not to send the beacon topics over MQTT, this would allow us to keep the beacon interval high (10 seconds) and avoid accruing payloads on Losant. A general whitelist/blacklist configuration for MQTT topics on the mc-Gateway could solve this problem.
Another problem, specific to Losant, is that if we use beacons for sensor readings (ideal for saving precious battery life) we need to use the Losant workflow to receive the MQTT event and then set device state based on a computation to retrieve the user data in the beacon bytes. The act of receiving MQTT in a workflow, and then using the workflow to set device state, both count towards the Losant payload limit. If we could define beacon user data mapping, perform simple calculations, and send results out on a renamed MQTT topic (in the case of Losant, a "set state" topic pattern), we could cut payloads in half on Losant. Yes, this problem can be solved by using MQTT directly on the modules, but this compromises battery life.