>you'll retain heat better with a dark, matte finish on your dome

No, they won't. There's a reason a perfect radiator is known as a "black body". Emissivity (a coefficient that describes the degree to which an object radiates, compared to a black body) is the exact inverse of reflectivity. That's why space blankets are shiny.

Of course, dark objects also absorb more heat, so depending on how much radiation you're getting from the sun, a black roof might result in a warmer home. But it won't be because it's retaining heat.

At the temperature that we generally keep our vacuum-facing surfaces they absorb far more energy in the form of light than the energy that they radiate. Energy management is tight when you're orbiting a small red dwarf star ejected out of its galaxy into the void!