I bought two tools, that are supposed to help me with balancing my horses feet.
One is from here:
And the other one from here:
Here are some pictures.
I must say that this Equine balancer tool is not fool proof either, but it does help visualizing where the hoof is high relative to the axis of the leg than just sighting down the leg, holding it by the cannon bone. So I don't regret buying that tool.
The other one is basically a horseshoe equipped with a dorsal hoof angle measurement feature. This one is also quite helpful as it allows to assess the surface plane of the hoof.