I posted this in another thread (that’s not visible here on the guest area), so re-posting the relevant info here as an alternate much more inexpensive (and easier) solution than messing with a mounting platform (though that one does look nice and appreciate you sharing).
In order to keep it firmly in place and upright, after trying a bunch of solutions I came across these adjustable elastic straps from Lowes: https://www.lowes.com/pd/Nite-Ize-2-ft-Adjustable-Bungee-Cord/5014218845 - I route these through the back of the cup holder bracket and adjust the length as necessary. A royal pain unless you use a grabber tool (that’s what I finally did) to thread the bungee through the small holes. These two clip attach to the 300C’s hooks. The unit now stays upright and securely in place in the event of turbulence.
