I'm curious why you chose Tilta cage (instead of ie Contineo)? And Aputure (used one's price seems great, did you look into Lilliput 5dII?)
The rig looks familiar :) Got Metabones Nikon sb here though. For shoulder support I went for Cowboy Studio's cheap one, not only because of the price but for
1) straight line from front handles towards your body so it's better to pull it against you
2) the handles come lower without the lowering parts for rods
3) you don't need to hold it with hands if you ie need to grab a battery from pocket, just let it rest towards the chest (can cause neck/back pain or head ache after couple of days shootings though.. Would be great to have a waist strap of some sort to lean the weight on waist instead of chest. Also heavy breathing becomes an issue with the chest supporting part, I might faint some day)
How do you like BMPCC as a RED user? A year ago, for me it was a wonderful jump from the past Canon HFS10 camcorder which I used for professional work :)
Oh yes, lately also got a LiPo battery for a gimbal, but there are converter cables on eBay for cheap to get it to power up the monitor (*) and with a split cable also to feed power for BMPCC.
(*) = Lilliput 5dII 7" ... tried a 5" Lilliput which didn't accept 1080p but only 1080i so it didn't work with BMPCC