[Mobhack]

Waypoints are probably useless for a beach assault since the beach AI is basically about driving straight for the nearest valid landing zone. The AI may well indeed clear any such that were set.

So just lay down the barges opposite to where you want them to come ashore and let the AI do its thing.

Beach assaults and wide river crossing assaults are weird things. There is just enough AI code to handle them, but little else. Trying to do anything that does not fit the stereotyped limits will go wrong. In both cases - the AI is really only there to provide target practice, beach and river assault scenarios are really only suitable for the human to be the attacker, with the AI as the defender.