I love your drawing. It shows how power injection works quite simply.
Thanks. For the record I am doing it like 'Option 1' from the drawing. Since both of my strings end at the end of my sidewalk I am just having to run one cable to my 'power block' that is being fed from my power supply (which is located next to my etherdongle by my computer). I am using a 18/3 cable and using 2 of the conductors as 12v+ power to each strand and the last conductor as a shared common.