The only thing I'm not sure about is the black couloring, having never done it.
The way my 'mentor' (who keeps hundreds of Wilts Horns on Salisbury plain) went about his Lleyn cross was by putting a pure Wilts ram to Lleyn ewes and then a different pure Wilts to that first generation of ewes who will then produce shedding offspring. These can then be put to whatever terminal sire you like. I suppose you could but a BMW ram to wilts ewes and put that 1st gen back to a Wilts ram, if I remember my genetics. The 1st gen crosses will not shed, but their fleece does kind of 'come off' a bit I believe, but will still need shearing. Don't whatever you do, put a ram back to its mother (or I wouldn't anyway).
As I understand it, the gene for shedding is dominant (or so he said), the reason it takes two generations (my hypothesising here, not his) is that it must be coded for on two different genes. Anyone with a better grasp of genetics that me is welcome to correct me on this.
My grazing is over a number of paddocks with access roads running through the site. Being both too stingy to pay for fuel and something of a tradtionalist, I always walk mine when I change pasture. I go on ahead with the bucket and whoever my lucky volunteer is walks on behind. You have to be gentle when you are walking them - when I have driven mules there was handclapping and so on - clap your hands at Wilts and they will vanish into the sunset. On the rare occasions that I'm not 'bucket guy', I whistle softly and tell em gently to get on, only raising my voice when they don't.
They are hard to pen and will jump out of a square hurdle pen - sometime tying a hurdle across the top helps, but I can't bring myself to tie two over, enclosing them completely. I am treating a ewe for 'lumpy jaw' (no - I'd never heard of it either), which is a 5-day course of intramuscular antibiotics, and I keep coming back and she is out of her pen, so now I've put her in a bloody loose box. Funnily, those who had to be penned at lambing (and she was one - good mother but had a rare case of triplets, one of which I gave to the local community farm to bottle rear) didn't jump, maybe they were exhausted, maybe they didn't want to leave their lambs, who knows?
They are a bit like hill sheep, from what I hazily recall (my godfather had a hill flock in the lakes when I was a nipper) - except they are big.