I cannot see a trail on the satellite images.
However there are photos of the road available at mapillary:

https://www.mapillary.com/app/?lat=48.09265136718801&lng=-114.50607096353997&z=19.9&pKey=203730128715250&focus=photo&x=0.45596984988065636&y=0.3585808194016511&zoom=0

With those photos, can you roughly describe where the trail and where the pictoglyphs are?

I think it is better to add it to the map at a rough position than not at all, maybe other mappers will see it when they pass by and add details.