Optimal masking solution for RVT blending objects with terrain

I’ve recently been playing around RVT in UE5 for blending objects with terrain ​and I was wondering what the intended masking solution for RVT actually was. The solution in all the examples I’ve found is based on absolute world z which is more or less useless for terrain with a lot of variation in z.

Are we supposed to make a bunch of different material instances to compensate for this variation in z or is there a more practical way to derive a mask. And would it even be worth it to add complexity to the shader given how many objects will be using it.

Im new to unreal and woefully ignorant of all things technical so forgive any potential stupid questions.