Some very interesting discussion on this thread.
Of course I mainly just skimmed it for now but I'll be back to read it in more detail.
And for what it's worth (or not) I've made a few of these short extensions (using standard connectors and 16 gauge wire) for people:
I didn't take a pic of it without the little cover over where the wires connect to the pins but if people are interested enough I could make another one and show the process. There is no heatshrink on the wires or solder inside but because of how I made it I'm confident that it won't short out like the one KareonKables had.
It doesn't get lower profile than the others that have been posted but I thought it might make a good addition to the thread since the wires exit towards the end of the card unlike basically all the other ones I saw.