In the Amarna letters, I'm not sure whether the Canaanite kings are "untrustworthy". They generally promise solid loyalty to the Pharaoh, to the point of fawning obsequiousness. Some are accused of collaborating with the Habiru, or having sold out to them. But the accused vigorously defend their loyalty. If there's a problem with the Canaanite kings of the Amarna letters, it seems to be their ineffectiveness and lack of rapport with the people -- is that what you mean by 'untrustworthy'?If the Danoi and the Philistines were established in Canaan as imperial-sponsored colonists, then so could such as the Apiru, all acting as proxy agents in the common goal of displacing the untrustworthy Canaanite kings.
Just because it's an artificial construct, doesn't mean it wasn't composed out of elements such as the Habiru, do you agree?Everything becomes much easier to resolve once one realizes that the entire 'Hebrew' construct, including the tribe of Judah, is a synthetic and political creation.