I have no idea what else I can run off the power supply really. I mean if I can I'd run as much off it as possible to reduce the need for outlet use. The enclosures I have listed in the amazon link are just placeholders for custom ones I am having a friend 3d print. The primary box will actually be 12x12x6 to give me plenty of depth for the outlets and housing the power supply. To be honest everything is very fluid at the moment, I'm willing to change just about anything if it will improve my build.
If you plan on running your Rpi and relay boards from the meanwell power supply you won't need the LM2596 as long as you are using the 5volt relays you linked. I have the same power supply running 2 8 channel 5v relay boards and a Rpi with no issues. I've checked the output of the PS with a multi meter and all 16 relays tuned on with the pi running with no power drop off or fluctuations from it.
Are you planning on using one of the premade boards like a wykat hat, theatrus blue acro board, Michael Lane board or build your own proto pi hat?