Just one of many ideas, the possibilties are endless. I'de always go for RGB leds over just white, allows for more customisation while able to still give you the same white as the white leds.
... unless, as in my use case, colors are not needed.
I'm too stingy to pay for the unused dry powder!
oki, in case i'll add some explanation.. I'll be busy for this week but you can simply use the serial gw example from MySensors for getting started, this should work. I didn't need to create a special board in arduino for this board, so if you're using it, you'll need to install&use the mattairtech SAMD21 board definition for the pin mapping.