Re: Itsaraphab.
Lonecat's right, there's the mandala system (the "galactic polity" in OW Wolter's definition) where a city and king exerts partial influence over another city, which might also be swayed by another neighbor. But what happened in the late 19th century is that Siam attempted to take all places that were of partial loyatly and incorporate them into a modern nation-state in the name of "freedom" (itsaraphab) from colonial powers. That's this mechanism.
Re: Doi Suthep.
Yes, Doi Suthep is from one of these border states - Lanna, a place (that Lonecat knows well!) that was potentially Siamese, potentially Burmese, or potentially independent. I thought this was an interesting nod to that, as to have a wonder from the very center of power (e.g. the Grand Palace) would feel strange if another civ built it. Here, it gravitates towards Siam, but is not limited to Siam. Doi Suthep is built earlier, but I'm thinking here of the expansion and construction of the road to it, especially under Khuba Siwichai.