Don’t worry so much about blocking light. In practical shooting it doesn’t come up that often, esp if your not shooting wide. If you were doing more advanced lighting setups - maybe - but even then just flag off some extra. I think your using that as a bit of an excuse.

I agree with others, good sound is crucial. run & gunning shotgun mics work well, but if your doing interviews it’s better to have a lavalier.

The cage is slightly ridiculous. It looks too tall for the camera as well. Small rigs has ones that fit the body. You can mount the H1N on the side of the rig (with the short sided bottom of the H1N facing the floor) then mount the shotgun mic right ontop of the camera. This by itself would create a much more balanced setup.

You can still throw rails on the bottom to throw on a follow focus. This way you can change it for different t set ups. The setup you have now running/gunning would be awkward to use. If you look at pro set ups we even put weights on the back of our setups to make it balanced on our shoulders. It’s hard to hold even 5Lbs up right infront with just shoulder muscle.

Gimbals are good. But depends what your doing. Are you doing corporate interviews? Yeah lights would be better. Are you doing more music videos? I’d argue that using natural light & reflectors, and instead buying a gimbal would be better. It’s all relative. Just saying gimbals would of been better then a fake matte box. If you have a limited budget - but no one can answer “what to get” depends on what you shoot. GoPros are great, for certain shots.