With virtual texturing all you’d have to do is render the spline geometry into the landscape VT as a render target. That’s how it works in Far Cry 4/5, where they can use a large amount of decals because they cost nothing after they get “baked” the first frame they appear. If Epic is working on modernizing the landscape, using virtual textures is the way to go, since it also eliminates the cost of blending terrain layers at run-time.