David. I am not sure if it helps but the one sucker i caught was on an unweighed nymph pattern.
Chris Stewart has noted catching red horse. Perhaps you can message him about it and what he used.
Perhaps you could even do some keiryu for them.
The white sucker i hooked hands down was the strongest fighting fish i have hooked to date. It had me chasing after it…up and down river. If i had red horse in my back yard i would try to figure out how to get them to feed.