Great stuff. Love the area. Having been to Monument Valley at least 20 times I have never seen a trailer down there. The first part going down or particularly the reverse coming back up would not be a good experience towing much of anything. The rest of the road is not too bad very washboardy in areas, a section of fairly rocky and rough and a couple sections of soft sand but the entrance/exit is pretty rough dropping down off the top into the valley. I know I would never take my travel trailer down it. They do have a good sized parking lot and shouldnt be an issue dropping the trailer for an hour or two to do the loop drive sans the trailer. The Moki Dugway as you found is not that bad it could be a chore with a long trailer 1st gear descent and hope no one else hauling a trailer meets you on one of the switchbacks but the road itself isnt bad.
