Simple question: With a 2017 12" rMB, how can I drive a 4K display @ 3840 x 2160 60Hz while charging the MacBook? My 4K display only has HDMI or DisplayPort ports (Dell P2715Q). When I am at my desk I want to have the MacBook in clamshell mode with external monitor, keyboard and mouse. If this is possible with my current monitor, I will get the 12" rMB. If it is not possible, I guess I will have to get the 13" MBP. My first choice is the 12" MB though. Thank you.