riltri,
I would go through the tunnel, but your route certainly works. If I remember correctly, 14 is steeper and higher than 20. But also doable IMO (I have pulled our 22' trailer over all these roads with my poor, under powered, Toyota Tundra). How do you plan to leave the Escalante area? The prettiest way by far (well, "reasonable way" anyway) is to head NE on hwy 12 to Torrey. But, if you don't like Hwy 9 east of Zion, then you really wouldn't like that route. Awesome country. Go slow, take your time, and enjoy the journey.