If the lead rope is allowed to slide along the high line, it defeats the purpose of this method unless stops in the high line approximately 10' away from each tree are utilized. Half inch hemp rope makes a good high line. Nylon is too stretchy. Multi-filament poly plus rope is best. It will stretch more than hemp, but is stronger, lighter, and will not soak up water.
Many horsemen use the lash ropes from their pack saddles for the high line.
A hitch rail can be easily constructed by tying a solid pole between two good-sized trees if a deadfall pole can be found. The horses should be tied on the opposite side of the tree from the pole so that the strain is against the trees rather than the rope-ties. The tying area must be located off the trail and away from water or boggy areas. An area with hard rocky ground that catches enough breeze to discourage insects is ideal. Some horses will become restless and paw while tied.