Black Canyon seems more like a mid day stopover. Look at the overlooks, have lunch, and move on.
Then we would go through Salida and up to Buena Vista, stopping somewhere north of Buena Vista.
This seems like a good modification to me. I only wish you could have a bit more time in the Buena Vista area, but you have to consider your over-all itinerary.
If you have towed from Durango to Ouray, in my opinion the Trail Ridge Road will be a piece of cake. We have been over it many times, but we have never towed because we always came in from the East and did our driving out from Estes Park. I think you will enjoy your visit to the Rocky Mountain National Park.
