I'm not sure how you can use this to help you but I experimented with a quest in Grizzly Hills and found out that you don't take any fall damage.
Quest: Mounting Up - Quest - World of Warcraft (alliance only)
Begins and ends at: Squire Percy - NPC - World of Warcraft
While doing this quest you collect carrots and use them to lure horses in which you return the horse back to Squire Percy. After I realized I wasn't taking fall damage I wandered off a bit, but remained in Grizzly Hills.
I wasn't dismounted from going away from the zone and took no damage what-so-ever from falling. Test it for yourselves, I may be wrong. Hope this helps.