The fuse in diagram 2 is pointless. Move it between m-unit and battery POS, or between Reg/Rec red wire and battery POS. The line of thinking behind that is if you are using a Lithium battery, they have sensitive rates of how much amperage they can tolerate during charging. If your R/R goes wonky, then it will blow the fuse and protect the battery from a drastic overcharge. If your battery is AGM, then go with option 1 (m-unit to POS)
By the way, you can delete the leg from AUX to Tail by using the menu option of "single brake wire" to operate both the tail and brake filaments from a single wire run. The BRAKE output willalways be on, but not at full intensity until the brake switch is activated (front or rear).