Dear client,
I write you because I already have a working mesh network library working on ATMEGA328P micrcontrollers, moreover, the library is in C++, it is not an Arduino sketch, so, modifying the SPI driver it can be ported to any other microcontroller.
In fact, just now I'm porting it to other micro controllers, so I can update you further, or develop the driver for the microcontroller you want to use.
If you are interested in this solution, please let me know.
Best regards.