Did some practice free mounting, idling and hopping today with the combination of a roofing harness and a rope hanging from the rafters of my garage. It’s a great confidence builder. Roofing harnesses are both common and affordable.
I find the rope alone is fine for practice. It gives you something to hold onto, but requires more balancing than something solid like a wall. The roofing harness on the other hand gives you that little extra bit of confidence to actually let go of the rope.
A couple videos of me practicing with the harness and my daughter riding in the woods.
I was actually thinking of using a climbing harness and a piece of climbing rope (elastic) for doing more complicated things on the uni. It would save your @$$ from falling but it would give sufficient freedom to practice it.
Unfortunately my roof isn’t strong enough, but for you it might be helpful to do as well 
EDIT: ok, the Roofing harness you mention is what I mean - Except I wouldn’t use regular rope but a climbing rope since it isn’t static and will actually catch your fall
I like the rope, could be a pretty nice tool for learning mounts. (I’ll have to test it next time I’m training a beginner and have a setup that allows for one).
The harness, I don’t really see too much benefit from to be honest, but I started unicycling young and never stopped, so I never got much of a fear of falling on flat ground…
it’s not just for fear, but you can actually slow down a movement (for example a 360 unispin) and practice it before you actually do it for real. That way your body can already get used to the movement making the actual move much easier
I’m planning on hanging a rope from about 5m, which should make it both more challenging and allow for a larger practice area. I find the harness just gives me that extra little bit of confidence as with it on you can’t fall. On a 20" uni that wouldn’t be an issue, but on a 36er it is for me and on a giraffe I would think it would be a huge help.
I had it set pretty tight so I didn’t fall very far before it caught me, but what I also found was that instead of falling straight down and being caught abruptly by the harness I was often near the perimeter of the lanyard and when I fell I would end up swinging in an arc towards the ground.
The first and most important skill to learn is the emergency dismount. Supports cause the learner to miss out on these lessons.
The developing the ability to get off the unicycle safely and deal with the circumstances without injury is vital and needs to be a foundation skill. It should continue developing along with the learner’s ability to ride at speed and on larger wheels and under different conditions. Obviously, by the time the rider is going down the road at 25 kph on a 36er they need a quite advanced set of dismount and landing skills. Like learning to ride, these skills are better first learned on a small unicycle.
I often hear of riders bemoaning getting their feet stuck on the pins in an emergency dismount. I can’t remember that ever happening to me. Learning without support (using a backstop), by the time I could ride I must have done thousands of dismounts where I consciously stepped off the uni. Repeat anything enough times and we usually get good at it.
I’ve been trying to ride as far as the muscles in my lower back allow me to each day, which currently is about 2 miles, and I get to practice a few upd’s each time. I think it’s just a matter of getting out there day after day and putting miles under my belt. It would be nice to have a smaller unicycle, but at present I don’t and my skill and endurance is improving a little each week. I’m hoping to be freemounting and hopping by the end of the month. Idling I think will take a bit longer.
That’s the spirit!