One thing that helps where the road you want is not covered is to use street view on a road that crosses the one you are interested in. In that case, you can look down the road you want from one that is covered.

I guess I am more traffic tolerant than some. I have not found the traffic count maps all that useful. The ones I have seen list all of the counts for the smaller back roads but I spend more time on larger roads where they don't list the volume. Sometimes I use the smaller back roads if I get somewhere and the road I am on is unpleasant or the mood just strikes me to explore, but then I usually just kind of improvise the route.