im just thinking logically here....... if i have a tank that is 30 inches deep and 96 inches long. and 1 radion xr30 gen 5 pro has 24 - 32 inches of spread..... as per BRS 8 inches off the water........ You can fill up that whole tank from front to back and you can fill up 90 inches of light from side to side. BRS even stated that the xr30 should be placed at "least" 22 inches away from each other to prevent hotspots and have an even par. so if im not mistaken and my math is correct 3 XR30 g3n 5 pros should suffice for a mixed reef tank. I am not planning of filling the whole back wall with rock and corals. im not planning to put rock against the back wall or the side walls. the rock and coral is gonna be centered in the tank with room behind the rocks for fish to swim and fish in front and side as well. at least till that starts getting filled up or i decide to go full SPS from wall to wall then at that point i would get more lights.
Your analysis seems mostly sound. Just remember when someone personally keeps a wall to wall acro tank advises you, it’s generally from their perspective. I’m guilty of that occasionally myself. If you are aiming to keep a normal mixed tank with a handful of sps carefully placed but a lot of emphasis put on polyps and euphyllia or acans, then minimal lighting is fine. You really only need 100-150 par or so for those type things to absolutely thrive. Your sps can just go point plank under the panels at the high points.