I've not done this, but regarding "How did you get the locking springs to swing over the big ass heat sinks?..... that's the one thing that has me baffled and worried......."
... they generally come with a separate adapter plate for the particular fitting (h7 etc), you just clip that in, then the bulb twists into the base plate.
https://youtu.be/kMcruu_QGks?t=3m18s