Following on my previous post, I had my steering column modified by TruPig Motorsports which utilizes a Nissan Versa EPS unit. With the design of this retrofit, the EPS while large is able to just fit in with the motor and control module clocked up running a cable throttle and Vintage Air Gen II Mini HVAC unit. I think it would still be possible to fit a DBW actuator back there as well.
Hope this helps someone in the future, it was impossible for me to find any information on fitting an OE EPS unit (not smaller ATV/Powersports units), DBW and AC behind the s30 dash other than people mentioning it is too tight/will not fit.