In his Lighting Interiors book, Scott Hargis advocates using Slik SDV-20 tripods for holding the flash guns, but they do not make them anymore. What is a replacement that you guys recommend?
Yes, you are right the Slik SDV-20 tripod is not in production anymore. A replacement that has the same key feature (the support tubes from the bottom of the legs to the center down tube) is the Slik U-8000 Photo/Video Mid-Size Tripod available on Amazon.
Scott recommends this type of tripod as a light stand because you can put all the legs close together so it takes up very little room so they can be put in room corners and other very tight spaces.