I’ve recently been planning theater lighting and ran into some similar issues. I have 12 coffers that will be maybe 20ft (generously) in perimeter, 240 feet. Budgeting 1.5W/foot makes for a lot of current on 12v lighting.
I haven’t really thought so much about RGB control, but I ran two 14 gauge, four conductor cables. I can run six coffers on each in RGB or split them and do four monochrome circuits. 7.5 amps each. I just roughed in the wires to soffits and back to where I’d install drivers.
It looks like I could control DMX units here if I wanted to do RGB, it would just be a matter of choosing drivers with the right features. I was planning on just installing magnetic LED dimmer drivers and controlling them with my overall zone control system.