To me, "close enough" is just taking:
8' x 12' 9.6" x 18' 7.68"
and bumping it to
8' x 12'10" (or maybe 13') x 18'8" (or maybe 19')

Again, not sure exactly what that will do or how much impact that will have when deviating from the ideal rations, but I think that if they are that close, the stuff IN the room will have a bigger impact than round up a couple of inches.

Farewell - June 4, 2020