Got it, although there's a discrepancy in its two connection points; one of them is placed further in than the other. So I'm using two multi-extenders in the back.
It now looks even more like it does in Ironforge!

^It hit me in that I could use the other control slots for different orientations of my bot: normal, backwards (for driving the wedge) and inverted; should make driving less confusing.
Along my way, a few days ago, I found out - simply because I wanted to delete parts faster - that I could press the Delete key after selecting a component to remove it. I'm told already that F12 displays their collision boxes and F11 takes a screenshot.
What other shortcut keys might I be missing out on? I would've liked to map my 'Inverted' controls to Home-Del-End-PageDown, but I don't want any key command conflicts.