A couple of thoughts.

GShiners and tilapia could work well.

GShiners can take cold water so they are not an indicator of if TShad can survive.

You can add TShad at low numbers and low $ amount (see Greg's comment)successfully if you do it before LMB and have time to let them establish. It can be done post adult LMB as well but it takes timing and higher numbers. You need a plankton bloom for long term success with TShad.

One point to think about WRT $ and balance and risk. If you have TShad for several years and adult LMB and the TShad die-off you need to do something or the LMB population will over eat the remainig forage and you will end up with a LMB crowded and skinny population. The same as if you stock tilapia a couple years and then stop. The LMB population grows to the forage base and if a big part of the forage goes away you get to many skinny LMB with not enough to eat. So its not just a current $ consideration it is also a population balance question.