For connecting the HW-30 to the auto xfer switch, to the panel, and from outside to the HW-30.... I prefer blue smurf conduit and THHN wires as it's easier to work with than ROMEX.
See my post #9 above for pics of the smurf conduit and THHN wiring. THHN in 10 gauge is stranded but not the fine stranded like the wire in rubber cords, its a much coarser stranding works well in the electric connections of xfer switches and the HW-30.
I sometimes add ferrules to the ends depending on the type of connection it is in. I have become a huge fan of ferrules on stranded wires.
As far as the remote indicator for the HW-30 goes, I put the one in my motor home, inside where I could monitor it. I would hook up and trust the box to do what it is supposed to do, and while inside I could monitor amp draw of various appliances, and of course, voltage, or if on the generator, the Hz. A shore cord connected directly to the HW30 really does need ferrules as the wire stranding is super fine. I did not know about ferrules at the time I installed it, but I wished I had known. (motor home is sold, went to Las Vegas). Last two pics are examples of 10 gauge and 8 gauge wires with ferrules installed
Charles