HELP: Mesh Painting Randomized Details on Landscape Spline Generated Road

I am using the Landscape Spline Tool to create a road.

Here's what I created for the material using vertex painting directly on the road which has a Megascan Blend Material applied to it.

The problem is I need to create this look on the entire road and it's quite long. I can't think of any way to do this but manually.

I'm guessing this Mesh Painted material will be quite large too as it is but it's also going to take a long time to do this way.

Other options I'm thinking of using with the help of Substance Painter are to :

1-  Have the 3 materials I've blended all in one material and somehow create a procedural mask for the 3 upper layers that make up the dirt, snow and ice/water with the mask creating that random blend automatically along the length of the road.

I'm not quite sure how I'd set this up in Unreal with this menu

2- Create separate copies of the same piece of road model and have a different versions of the materials with the details and then randomize the models?

With this method I am seeing this problem when I used some test models with different colors to try and see how the Landscape Spline tool is placing them.

I would also have to somehow randomly place the models but also have it so they all are interchangeable and tileable with each other.