For starting a brand new tank and with the opportunity to plan ahead something like this in tank refugium sure would be a winner:
https://forums.saltwaterfish.com/t/101556/in-tank-back-wall-refugium. the idea is you can simply use a thicker tank and have this replace any external sump/refugium. And that way have as much or more free space for corals or fish. With an outdoor tank the plant side might even be on the sun side so the macros could provide shading from the more direct sunlight.
make sure you use some calcium carbonate based rocks or substraite and there is water flowing around it. Aragonite sand, crushed coral, crushed oyster shells, dolomit, Etc, Etc. And even an undergravel filter to unsure water is flowing through it. That buffers calcium and ph.
Starting: add filters/circulation, add substrait, add saltwater, add plant life. fill to top.
run system for a week.
then do the rest.
rest would probably be add rocks. run for three weeks. (lets parasites die off). Add 1 male molly/20 gallons. Dont feed for a week. use light feeding for two more weeks.
then slowly stock the system as you desire.
recommendations: don't do water changes just replace evap water. use tap water. Don't use skimmers. protect the plant life and insure it is thriving. Don't add cleaner crews. testing optional. let the tank tell you what the status is.