Neat idea with the paint brush. I use blond beaver guard hairs, but blond beavers are not always available. (Go figure!)
What thread do you use for the sherry spinner? Thread can make a big difference. I have seen instances where the dubbed body was not highly UV reflective, but the thread showed through bright in the UV. Here is a Light Cahill photographed in reflected ultraviolet light:
The cream hackle sure stands out, as does the cream thread of the head. So, your larger spinners, using cream hackle, would be quite visible to the trout. I can't speak for the twinkle organza regarding UV reflectance.