What about using standard-height, non-moveable wickets, like at specialties? The height divisions are over/under, so the actual, exact height of the dog doesn't really matter, right?
So, for AKC you would have a 10" wicket, a 14" wicket, an 18" wicket, and a 22" wicket. The wickets are made of a solid piece of metal, like a cricket hoop. No up-and-down swingy arm.
If the measuring judge puts the 10" wicket on a dog, and there's daylight under it, the dog jumps 8". If s/he puts the 10" wicket on the dog, and the feet swing, the dog jumps 12" (after double-checking it with the 14" wicket). This takes away the messiness of the wicket-arm moving, the dog wiggling, and the handler bickering about three-eighths of an inch.
It's not perfect, but could a system like this work?
Interesting discussion.
This is how it's done in the UK. As far as I know only the KC actually requires a measurement before the first competition. I certainly had Epic officially entered (doing training) at other venues before he was measured and the process there was just to guess at which height he would be. I had a load of agility people tell me he was small but I had my homemade wicket on him and thought it would be touch and go. For Small they have to be under 13.75" and I had shown him in breed where pretty much all males are standing at least 14.75" (and some) and he didn't look tiny. Thankfully he measured into small - just - but he was freaked by the wicket/measurers and not standing very steady. He will have to be measured again in the next 12 months and I'm hoping he will be more relaxed and still in small.
He can and has jumped medium height but being on the cusp at the bottom end it would have a big impact so I would be completely gutted if that happened. We don't have preferred or anything similar apart from a few special classes at independent venues and I think it is a real shame, especially for people with dogs just into large.