Main energy gain happens because of the radiation.

I think that the best combination is high thermal mass structure followed by the insulation inside. This way the heat is not easily transmitted to the inside and the thermal mass can cool off to the outside during the night.

Of course when the heat finally does get inside then it is trapped because the house will act like a thermos and only way of cooling would be the by circulation of cold air.

Problem of windows can be solved by outside blinds (or shutters but blinds are better) and IR reflective coating.

There's newer double/triple pane windows that have blinds built in which are nice

Are you aware of anyone using eutectic salts in the walls in the desert? I remember reading an article from the 70s about it and it seemed well suited for desert environments where there's a large temperature swing from day to night. They would absorb heat in the day keeping the house cool and release it at night keeping it warm. If I remember correctly, the difficulty was finding salts that worked on the right temp range