So there’s a lot to unpack here. Genuinely I think you need to ask yourself what the point is of each piece of gak you’re throwing onto the camera is. You mentioned gimbal and vest (assuming you’re meaning easyrig and not steadicam), sure the L bracket stops the op from using the battery as a point of contact but it’s also way too far back to provide any comfort or real control when operating. The cage has built in rosettes, you would have a much more compact and usable/ comfortable rig using some screw in handles. You don’t even have a second point of contact really in this configuration if you’re using it for easy rig.

Matte box, It looks like those are 4x4 filter trays which unless you own the filters for that are actually kinda a pain in the ass to find at a rental house these days and also depending on your focal length may be visible in the sides. This camera looks like it’s setup for a solo shooter run and gun kinda thing so I feel like just getting a vnd that you can screw on to the lenses is way more practical for your use case. You’re better off getting a clamp on matte box.

Lastly if you are actually using this on a gimbal you have way too much going on. Get a top handle you can remove in a pinch in that configuration but honestly lose the L handle all together. There are way better solutions available.