i need tips with sizing of the rear wing (chord line , vgap, hoverlap , AOA )

Hey everyone, currently working on the dual-element rear wing (naca4412)for our FSAE car and getting a bit stuck on preliminary sizing.

There's a ton of conflicting info online about slot gap parameters and chord ratios, so I want to make sure I’m starting from a solid, reliable baseline before dumping time into CFD sweeps.

Does anyone have good rule-of-thumb ratios or solid reference literature for:

main element and flap AoA

main element and flap chord length

vertical gap and overlap

and i also wanted to know how do you approach your design do start of by finding the optimum AOA of the main element alone first then adding the flap and finding the configuration with best L/D ratio

Any book recommendations, SAE papers, or personal insights from past builds would be massively appreciated!