HF Arduino Beacon project

I plan to make an Arduino CW beacon.

This are the features I was thinking of:
 -Connected to ICOM IC-7100 via CI-V serial interface;
 -Can send Baro, temperature and humidity;
 -Send at regular time intervals;
 -Send in several frequencies;
 -Send at various power levels.

Will be based on a Atmega 328 uC and will have a DS3231 RTC and BME-280 sensor for meteo info.

DS3231 was chosen for RTC because it have a very precise, thermo-compensated oscillator and keeps time very accurate. Also the local temperature is available for processing it.
BME-280 is a high precision array of sensor measuring relative humidity, temperature and barometric pressure.

It will operate from my second location in KN25UC, abt. 6 km West form Campina and 90 km N from Bucharest.
I am using a Hustler 4 BTV vertical multiband placed directly on the ground and one of my ICOM radios.

If you have suggestions, please leave a comment below.

MFJ-5124I cable schematic

Pin 1 (Key) connects to the Tip of 3.5 mm Stereo Phone Plug.
Pin 2 (Start) connects to the Ring of 3.5 mm Stereo Phone Plug.
Pin 3 (+13.8V) connects to the Center Pin of Power Plug.
Pin 4 (Ground) connects to the Sleeves of both 3.5 mm Stereo Phone Plug and Power Plug.