A BC with 4 shoulder D-ring spaced near the collar bone is redundant. If you clip off onto the upper D-rings, your danglies will block out access to your lower D-rings. The only time I feel more than 2 shoulder D-rings is necessary, is if you put the other (or pair) of D-rings lower down where your rib cage ends. I've seen friends toying with this setup when we perform scientific surveys; although it's using a Bp/W and single weave harness. They end up clipping their slates or reels to separate D-rings for ease of equipment navigation.
For your purposes:
Clip off your light(s) to your shoulder D-rings and loop the ends down with hair-ties onto your shoulder straps, or rubber inner-tube loops, or bungee-loops.
Console/gauges can go to a D-ring of your choice. Reels can go to your waist D-rings. For a SMB, get a Cetacea clip with a split ring on one end, and a male clip on the other end. You can then clip your rolled up SMB onto your female quick clip that's above your pockets. Use a bungee loop to keep the SMB rolled and the Cetacea clip snug under so the whole unit flaps less.
Camera is clipped off to a shoulder D-ring of choice using a double ender bolt snap to the lanyard. (I made a bungee system so my camera is connected directly to the double ender, less dangly).
Small slate can be pocketed in your BC. As can a fingerspool setup with an SMB if you so choose.
This is basically my old setup that I did with my Sherwood Axis. On my heaviest scientific dives I was carrying an 8.5x11in slate, 2x 50meter tapes, a PVC measuring pipe, 2x lights, SMB & finger spool, catch bag filled with ziplock bags, and a camera.
Used every single piece of equipment (minus one flashlight) and didn't feel cluttered at all, but you have to have some forethought into how you clip those things in, where, and how you're going to access them.
Often times the easiest clips to use are bolt snaps.
If you don't see yourself using an item, don't bring it. An SMB & reel can be left behind if you're sticking close to shore away from boat traffic. Likewise a second flashlight can be left behind if you only use one to look into dark corners during daylight. Make a good dive plan with buddy briefing and you can leave the slate behind.