I made some more adjustments. I seem to get the best results with RST left at the default of 12 and 1_2, 3 and 4 lowered to the minimums for a 50 inch as shown in the attached.
No artifacts that I can see. Blacks look a tiny bit brighter than with RST at 1 or 2 but still can't be measured by my iD3 so I'm fine with them. No red tint in letterboxes in a dark room but I still perceive a little on the edges of the screen on a full black screen (And I can live with that). Black screens are also more uniform now without the splotchy patches.