I made an adapter cable to go from the BMW solenoid to the original D2 connector. No idea if this thing is polarised or not so its long enough to cut and re-terminate if I need to swap the connections over.
Plugs in under here
and loops over the top of the rack, which is neater and a simpler cable run than the original which went underneath and flapped about.
Since I used rivnuts in the chassis legs instead of studs, the original heat shield nuts weren't going to work, so I turned them in to bolts

Start with the part on the left, shorten it slightly, turn down the thread diameter a little, then screw the nut on to it.
They are tight enough that the stud will unscrew with the nut if I ever need to dismantle them again, effectively turning the assembly in to bolts.
Waxed the engine bay. Obvs.