It may could be done if there are only threadfins and WB. As you say, plenty of plankton for the filter feeding of THS. The amount of shad needed would pretty much shut down excess BG survival. Golden shiners could help, but would stay in shallower water and help feed the CC and larger BG. CC would help control larger GS.
Bruce, do you know the approx. conversion rate of WB vs. the HSB of 2 to 1?