I would schedule ten or eleven days for such a trip: Seven days (minimum) for traveling the 3100 miles via surface streets and small towns, a day to visit my friend in Jackson, a day's worth of time spread out over the trip to actually stop and see some of the amazing sites that I'll be spending all that time driving by, and a day in reserve to sit out any nasty weather and wait for the road crews to do their jobs. Note that at least eight of those days are used to fulfill your design of the trip. Only two days are set aside for safety and enjoyment.

I will note that when I was younger, I did a similar early spring trip, Eugene OR to York ME in seven days and was absolutely miserable for the last 4-5 days of it. But I had left myself no margin. It was one of those learning experiences that everyone on here has had and to which we unanimously vowed "Never again".

AZBuck