I'm just wondering if I can't just do the following
Arduino -> USB-C
GND -> GND (A1)
5V -> VBUS (A4)
SS -> CC1 (A5)
SCK -> CC2 (B5)
MOSI -> D+ (A6)
MISO -> D- (A7)
The CC pins are "configuration channels", in a way I guess you could consider SS (Slave select) and the SCK (clock signal) to be some kind of configuration.
VBUS is for VBUS power, so that should be ok for the 5V?
A6 & A7 for data?