The easiest way is to land the full sized 250.66 GEC in the meter/CT can and be done with it. Some PoCos may not allow that but it is the preferred method here.
You use an RNC nipple to get through the wall to the service disconnect with 3 (or 4 for 3p) wires and hit the bus with the MBJ. That satisfies the inspectors who don't want a parallel neutral path although, on the line side of the MBJ, I am not sure that matters.
A agree as soon as NFPA allows "taps" the idea of an unspliced GEC flies out the window.
