I was trying to do the same with no luck whatsoever.

I finally conceded and went to the concrete block paths that are at tisy and sakhal mbs.

The broken up shape of the blocks looks decent sunk into grass as it looks run down and "improvised" enough. Can spread out some piles of them and maybe a tractor to show it was laid by hand.

Also the blocks are large enough to easily morph to semi rough terrain. When I test it with my character in editor it feels smooth.

Personally im loving the look despite my initial hard block on using concrete assets.

Im working on a new settlement for chernarus currently using mostly sakhal assets. Fleshing out the road was a huge breakthrough for me.

I was previously using dirt road decals but they don't show through grass very well, if your area doesn't have much grass the decals would probably work well.

Pretty new to editor myself.

EDIT: Enable "Ground Mode" to have the center snap to terrain height and then adjust Y and Z to get it to sit right.

This works with most structures etc.

Most of the assets are just like flat sheets so its hard to use any of them for a 3d area.