The little 4 side reference image That i grabbed off of google images says Sherman 1944 , that's all I can say . I guess that its about 80% finished , some details are not there yet . and Im going to re-do the tracks
Using a duplicated layer with the same terrain material is probably the most common way I know of, it is, however, a 'hacky' and sub-optimal method perhaps this should be flagged as an issue and something that actively needs to be added as a feature, not only for roads but for other decals too, there already exists a methodology for it in the form of the allow on statics option that used to be a thingThat is how I do it, usually some dirt texture, which adds additional detail and realism to the level, since roads are not build on grass, in reality they clear the area before they build roads on it. If you really want to keep it grass you can make a second terrain material with the same texture, but remove the ground cover from it, so you can control where the ground cover is.The only way I can think of to remove ground cover is to paint under the decal with another terrain material.
Ohterwise I would advise not to use my assets from my old packs, but use them from the actual Uebergame repo, since they are often the improved versions and bad ones sorted out. The grass you are using is one of my first attempts, which I was not satisfied with.