I really like some aspects of your design. It reminds me of several rigs meant to duplicate the Aaton, but those are either DIY rigs or kind of expensive and a bit silly.
What I like most is the lightweight but sturdy take on a top handle. Leaving it hollow makes it easy to run cables, as you've done. Also, mounting the EVF or monitor on the handle makes a lot of sense to me, especially if it were mounted with an upgrade from a friction arm to something more sturdy and easily reposition-able, like the Edelkrone Monitor Holder or the simple 15mm cross-rod of the Lanparte BMPCC Rig. I tend not to trust hanging a field monitor off either a shoe mount or a friction arm.
Having essentially 2 vertical cheeseplates is also great for mounting additional equipment, and I like that they're as wide as the rods, for a big shoulder pad and room to mount internally, if desired.
My biggest concern would be with the center of gravity, which ideally should sit right over your shoulder. I doubt that the Sony NP power supply is heavy enough to offset the glass/monitor/mattebox/cam in front of your shoulder. Couldn't you move the camera up and back, and attach the handle to the very rear to get a less front-heavy rig?
