outdoor lighting setup for shooting interviews, with changing and mostly low light (sunset through evening)

I’m shooting interviews with WW2 veterans living in Israel, to preserve those incredible stories. Due to COVID, I’m unable to continue shooting those interviews indoors, to avoid potentially infecting the interviewees. I’m trying to achieve an as-high-as-possible level of photography. My ultimate (probably unachievable) goal is a 60-Minutes-esque interview feel and look.

Currently, my main issue is lighting. It’s too hot to meet in a park before the last hour and a half of the day, so I’m shooting through the sunset time, when much of the interview takes place when it’s already dark.

I’m shooting with a Canon 70D, using a “pancake” lens (Canon EF-S 24mm f/2.8 STM Lens), in an attempt to achieve shallow depth of field. (I also have an ND filter, but it’s irrelevant for those lighting conditions)

As recommended by Doug Jensen, I’m placing the key light on the side to which the interviewee is lookin towards and the back light right behind them, or slightly on the side:
Doug Jensen basic 2-light setup, as described in "How to Set Up and Shoot Awesome Interviews with LED Lights"

My current lighting gear:

  • Key light: Godox LEDP260C Bi-Color LED Light Panel (3300K–5600K color temp. range)
  • Back light: Godox RGB M1 LED (2500K–8500K color temp. range).

I’d greatly appreciate any recommendations regarding a setup for this unique situation. Mind that I’m doing this all alone, I don’t have a team with me.

I was thinking of adding a fill light on the other side of the interviewee, in a similar angle of the key light. Can a reflector do the job? Or should I get just another Godox for this task?

One of my main issues is that the background is literally changing throughout the interview, which makes editing harder.
I was also thinking of using a background/backdrop that I will bring with me, but due to the fact that I’m doing this alone — I’m afraid this would be just too much equipment to carry and that it will take too much time to set-up. Is there some foldable recommended solution for such situations?

Just for example, this is how my latest interview looks (shot with the gear and setup described above) throughout it’s “timeline”:
Semion Zaslav 17.09.2020 interview - phase 1

Semion Zaslav 17.09.2020 interview - phase 2

Semion Zaslav 17.09.2020 interview - phase 3

Semion Zaslav 17.09.2020 interview - phase 4