- burning the bootloader to the Atmega328, configuring the DIYino board as an Arduino Nano
Why not configure it as an Uno? That way it will have the 500 byte Optiboot bootloader instead of the 2 KB ATmegaBOOT_168_atmega328.hex. That extra 1.5 KB of space could come in handy with LSOS getting so close to the limit. The other benefit of using the Uno bootloader is the Nano one has a bug that can cause infinite reset loops if you set a short watchdog timeout in your sketch.
Does this bug affect all boards or only certain "technology corners"?
does the uno also have an Atmega328P? Because I once tried to bootload a non-P as nano instead of mini and it failed...