BMPCC4k: Mounting Upside Down to the Zhiyun Crane 2. It works!
I wasn't sure how to mount it to my Zhiyun Crane 2 so I ordered an offset mounting plate. Of course, I'm too impatient to wait for the plate to arrive. So yes, you can mount a BMPCC4k upside down as a decent workaround.
I just received my Blackmagic Pocket Cinema Camera 4k and borrowed a Lumix 14-140mm f4-5.8 lens.
I mostly shoot 1080P. This test was shot with the BMPCC 4k at 1080P 24 and 60 fps, with ProRes 422 encoding using "Film" color and later color corrected using Davinci Resolve's "Auto" button. No color grading applied; I'm still learning and really don't know how. The shoulder camera is a GoPro Fusion 360.
Here is the adapter plate I've ordered. I'll post an update with my results. https://amzn.to/2JCsTyI
Update: It works nicely if you remove one of the 1/4 20 screws. There are two and one gets in the way. Remove the 'fixed' one (the other slides) and then mount the camera and center and balance it up.