A good mule is best, but they are also the rarest.
The wrangler (you) has to be smarter than the pack animal. That's why most packers don't use mules or Arabians.
Being green, you would probably do better with a horse each, IMO.
For what you want, renting would seem to be the best thing. It does not sound like you want to do other equestrian events or activities. You would do best with a short stout horse, 14 - 14.2 hands.
