Okay, started the install today. Taking pictures along the way, so I'll do a write up as soon as I'm done.

Turns out the antenna extension cable that came with the Dynavin E39 D99 isn't long enough for the X5 (should've compared it up to the Fakra cable beforehand; Fakra cable length is plenty). Have to go pick up a few more feet of antenna extension cable tomorrow to connect.