I do the Bear Flat Trail a lot. It is a straightforward trail after a short climb up the road from the ranger station. The only exposure in summer is to the sun. Most people single out the switchbacks past Bear Flat as a particularly hot section. Once past those, most of the rest is along a scenic ridge. There are a lot of nice views in various directions. It is a steep trail, but definitely a trail all the way.
My GPS usually indicates about 6.25 miles from the Ranger Station. Times vary widely. I typically plan on three hours up, but I tend to hike quickly. I would guess that 4.5 - 6 hours up is typical.
I have posted many pictures of this route over the years.
Here is one trip.
