I’ve had mixed results manually white balancing with a card and video lights in wide-angle. Ive had nice color results at times, but I’ve found it can sometimes be difficult to conveniently get the card in the right position to accurately represent the subject distance and accommodate the angle of the light beams while holding the card. Especially if you’re angling to avoid backscatter.
In my experience, setting the WB to light temperature value doesn’t quite get the color I’m looking for if there’s any ambient light, even with higher power lights blasting.
I’ve generally had nice results with Sony’s auto WB with video lights, making sure to lock it in so it doesn’t shift during recording. Perhaps some tweaking in post, but Slog is pretty malleable.
*I shoot with a Sony A7Siii, SLog3, 2x Kraken SFM 18000 without filters