Lightbox required with LED Lights?
Depends on how big the panels are, I'm assuming these are LED panels. Really, you only need 2 lights for the subject, and 1 light if you want to stylize the background. You can use a foamcore if you need fill. You want the panel or box to be as large as possible. I shoot most of my interviews with a 1.2K ArriSun HMI, but it uses a large Chimera with grid. So it's very very soft. Then boom a joker either over head or from and hitting the person's face on the short side of the frame. This gives a nice cut out, and the soft light from the Key Light is perfect. If you cant get your hands on a large softbox, depending on the output power of your LEDs, bounce. The best lighting, and nearly all lighting in Hollywood, is bounced light. Bounce your lights off a board, carry different sizes with cookies, and cutouts, make some dots to shape the light. For background, a single 1K tungsten lamp will do, you can gel it, or wrap it black wrap, poke holes in the black wrap, tear it, to create patterns, or natural shapes. If portable is key, you want your lights to be as high output as possible, smallest package... this means HMI, with LEDs, my biggest reason for not jumping over, is you have to carry a lot of extra grip equipment to get the lights where they need to be... because the output is a fraction of what an HMI puts out.