This is the Australian thinline site: Link
I have the plain cotton trifecta pad - Love it, show in it - It looks neat and tidy - And my horse is happier.
I haven't seen the woolen one, but think it might be very $$$$ - Although I don't doubt very nice.
It strikes me that what you want would be hard to find... Most have the fleece covering the underside then rolled over just at the edges. The pad would have to be a good inch or so bigger than the saddle for the wool to be attached without creating a pressure point/ridge - So you may loose some of the streamlined look you get with the hacking numnah's.
I'm not really a hacky, so sorry I am not of more help!