Steps taken:

• Made test setting to test the serial communication and possible use of timer trigger from RN2483.
• Use of logic analyzer to inspect serial traffic between 328P and RN2483 reveiled strange behavior. It randomly seems to work.
• Retesting with another RN2483 and with a Pro Mini 3.3V 8MHz gave same results.
• Ordered the Atmega328PB chip with 2 hardware UARTs and PCB to solder it on to ensure solid communication, this will impact my board setting.

Details of progress and next steps in main text of project.