The evaporation from a tank that size will be terrible. Maybe look into an exhaust fan. My tank is 8' 250g, and it gets very humid in my house. I installed a whole house fan, which is great during winter, but during summer months it's too hot to use it.
Running multiple skimmers will get old. I would look into selling the 3 you have, and get 1 big one. Look at Aquamaxx, they sell a very large skimmer for a tank that size, and it's not terribly priced. If you want to save money on flow, throw a few Jebao WP60s. They move a ton of water. You can probably do 2 gyres, and 2 WP60s, and call it a day. For a tank that size, I would sell the Arid, and have john from AA build you a custom sump with a large refugium. Get a quality grow light, and that will help keep nutrients down. He can even incorporate an area for frags down below. Save you from having to have a separate frag tank. For a return pump, I would think you would want to run one of the large Reeflo pumps. And I know they are energy hogs.
Having a tank that size requires the right equipment. Don't waste time setting it up with mismatch equipment, only having to redo it a few months later. Lights you can skimp on for now, that's no biggie. (And will probably end up being the most expensive part of the tank.). If you don't already have a mixing station, you should budget that into the build. Remember more evaporation = bigger ATO reservoir. I use my 65g ro/di reservoir as my ATO for my 250.