Just curious if your brake cable is also internal to the bar ?.
If not, I’d question why bother with E-Tube internal.
As well and throwing a monkey wrench into the works, it’s cheaper in a 1X system to use a Shimano XT bar display unit, SC-MT800, in place of the bar end/under stem A Junction. It combines BT wireless, charging port, has a gear display, and 3 E-Tube ports. Saves about $85. Adds a device to the bar.
If you are NEVER moving to 2X on this system, I think they make a specific L shifter for 1X systems that has no Di2 function. Thus no need for an E-Tube wire to that side. My XT Di2 system has the bar display, a cable to the R shifter, one 1600mm cable from the display to the seatpost battery, another 1600 to rear derailer. Also saves on a B Junction.
Last edited by Steve B.; 06-19-20 at 07:20 PM.