Why not use the background for lighting instead of the dome? It casts highlights and shadows, the dome does not. It also renders with less noise than the dome. this is illuminated with the background only. No lights and no mesh emitters. Real shadows, real highlights, and background image just like the dome.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740