The breakout board looks fairly easy. I2C bus lines should be short. I2C is designed for connecting devices all on one pcb.
I am not sure how to use the I2C multiplexer with the regular library(s).
Configure once and all subsequent "address" go to a specific device. Should be easy.
The SPI approach will always get the correct class object transparently.
The multiplexor will need you to insert a fresh "address-device#" sequence before changing object.
David.