@Ezequiel *******
all I said was that a visa on arrival can't be converted to another visa type inside the country. You either get a tourist visa and come back OR as you just pointed out, get the 90 day Non-O visa issued from a consulate <- IF you can find one nearby that will do it.
Nope kids under the age limits I outlined have no issues with overstay, exiting/re-entering, getting visas, etc