Awesome! Thanks for the help @chenbeier. Glad to learn it'll result in a pure 24K gold powder.
I'm expecting to boil away a large portion of the aqua regia, then add the remaining liquid/acid into distilled water... and not the other way around! That should lower the pH. I'll test with a pH strip to get it as neutral as possible. Got a wide open space away from people so the fumes will be at least 50m away from any passerby.
NOTE: Looking into the Vitamin C/Ascorbic Acid suggestion.