Do you have enough clearance between the front edge of the shelf and the closet door to pull out the SRSR and work on the connections? It will cost you a little vertical space, but you could install your own top shelf above the California Closets top shelf.

Small stuff, such as ROKU, TX's, and possibly the router can be Velcro mounted to the walls. I often mount network switches vertically to the side wall. This gives me front access to the LAN connections and requires very little shelf space.

The worst part of this mess will be dealing with the modular power supplies. I'd be tempted to skip the modular's and use larger, central supplies and a small power distribution panel.