Powering 600 WS2811 5V LEDs by using larger voltage power supply and DC:DC convertors close to the LEDs
that sounds like a good plan.
If you are a struggling artist there are inexpensive DCDC modules available on-line. I like the ones from QSKJ  and &quot;MH&quot; (QSKJ has a website, MH you'll have to search &quot;online marketplace&quot; for.
If you are a professional artist the likes of Traco and MuRata make DC-DC modules that cost more and are possibly better quality.
All theses manufacturers seem to test their modules in a blizzard if you don't want to use a cooling fan run them below about 60% of their claimed capacity. I'd use 5A modules but only ask 3A from each.