It costs more than the small ones, but I got one of the RAM mounts from Amazon. It's easy to attach to just about any case, you can mount it anywhere and it's really secure.
Highly recommend the RAM suction twist lock, but have to screw it on to the Stratux mount with 4 suction cups. Those four suction cups wouldn’t hold for me in the sun and mid-flight it was popping off the window. RAM suction was a solid upgrade:
https://www.amazon.com/dp/B001447JYG?ref=ppx_pop_mob_ap_share
I bought the standard case, but added the ram suction cup. I’ve used the ram products in the airline cockpit and they are tremendous. I’m glad I went with one of these as opposed to four “normal” suction cups. This is just my personal PSA. https://www.amazon.com/Mount-with-Suction-Cup-Base/dp/B001447JYG