https://www.escapeforum.org/forums/a...4&d=1612491891
Wiring diagram.
The upper right shows the wiring harness coming into the trailer junction box, including the black (+12v) wire connected to lug #2, also shown in black.
Three wires connect to the trailer side of lug #2: the 8awg wire to the battery, the wire to the breakaway switch, and the wire to the power jack. So, in concept your idea to tie the power jack into the breakaway switch makes sense as it is going to the correct lug. I can’t advise you on using the breakaway switch wire for double duty. It seems unlikely that the breakaway switch and the power jack would be used at the same time.
Notice that the diagram shows a 30 amp fuse leading to the power jack and that the jack is grounded to the frame. Notice also that neither the power jack nor the breakaway switch run through the battery disconnect.
What you don’t want to do is tie into the wire returning from the breakaway switch back into the trailer and connecting to lug#7. That wire is hot only when the cable is pulled.