I came up with the no-twilight myself, figuring that it's possible the planet's atmosphere can be of a constitution that does not diffuse light like ours does, and would behave more like a planet without an atmosphere, like Mercury, or our moon.
When picking Demakor and Gallant III, I was assuming the Loedar and Gallant planets have different rates of angular rotation and that at this time of the story they could be within 2000 light years of Jirdia, and closer than Elistra / The other Gallants. I also now (finally) understand that the Gallants and interior planets have axial tilts and do not orbit on a flat plane as the Kadrus map suggests, and that I ought to chage the Kadrus map to indicate this.