What it is like here
Cambodia asks less of a foreign parent than anywhere else on this site: a business visa extension is renewable indefinitely with no income test, no employer and no age limit. What it asks a lot of is the school budget — Phnom Penh’s flagship international school charges close to thirty thousand dollars, which is Western European money in a country at a third of American prices.
How the process works
Enter on an ordinary (E) visa, not a tourist one
It is the tourist visa that cannot be extended; the ordinary visa can, forever.
Extend for twelve months
Done through an agent in a few days, at a few hundred dollars.
Decide which tier of school you are buying
The gap between the flagship and the mid-market is roughly threefold.