Anybody had/found this rattle? (passenger left knee area)

Good morning. I have a 2017 SR5. I've been chasing a rattle for 6 months off and on. Like many rattles, it happens when the temperature drops below 50 degrees, especially when I transition from my garage to the outside temps in the morning. It doesn't seem to be totally dependent on bumps as even a more textured road surface will get it rattling/buzzing. It sounds more plastic than metal. I've pulled all loose objects from console and glove box. It seems to be rattling around the passenger's feet, maybe even near his/her left knee, almost like part of the console/lower center dash. Could be under/behind glove box, I suppose. I've strategically placed felt tape where I can click panels together. I've pulled the seat bolt/frame covers. I've secured the rubber splash guards in the wheel wells. Before I start pulling panels, do any of you have suggestions or have you had the same rattle and found it? I would rather avoid the dealer as I can't reproduce it unless it's cold and when I'm transitioning from my garage to the colder temps, but it's pretty damn reliable under those circumstances. Thanks for any experience and suggestions.

 

I'm having a rattle right now in the driver's left knee area and it sounds like a clicking or flapping.

For me I think it is the splash guard as it has some play when I wiggle it.