I'm certainly no expert on the subject, but here is my approach.
Instead of using custom white balances for every lighting set up or modification, would the purchase of the X-rite ColorChecker Passport be an option?
I purchased one a few years ago, then set up a database set of shots in Lightroom for different lighting situations (colour callibration profiles within Lightroom) eg: Perth sunny, Perth Cloudy, Studio lights, Speedlite etc.
On every shoot, no matter whether its indoors or outdoors, I take my first shot of the ColorChecker Passport. When processing the shoot I choose the appropriate colour callibration profile within Lightroom, and then white balance off one of the grey squares on the shot of the ColorChecker passport. I then sync the rest of the shots with that profile and white balance.
Hope that makes sense.