As widely acknowledged that, maximum trimmed Clmax is more import than CLmax_clean for tailless configurations like BWB and flyingwings. However,  this issue relates to flow separation, control devices and moment,  I've only seen it is calculated using CFD tools. Since I'd like to treat this one as a state variable in optimizations, I wounder if there's a way to predict this parameter using low fidelity tools like Lifting Line theory, Xfoil etc