Looking forward while walking with navMeshAgent

Hello everyone ^^ I have a pretty "complicated" map as you can see in the picture on the bottom, whenever I want to instantiate a unit, I have to select a tower A where the units going our from, and a tower B where the units should go, the problem is I couldn't find a way to make the units always look forward and rotate whenever needed, is simple cases like in direct paths, it's easy, I just use look at, but for example if I try to move a unit from a blue house to the one in the center right, lookAt won't be what I need, what I am asking for now is a way to make the unit always look forward and rotate on curves, if anyone have already tackled such a thing, let me know ^^