The Restayn book,
Tiger I on the Western Front does have several photos of 121. This vehicle has a distinct oil stain on the front of the hull and is also characterized by a second tool box affixed to the starboard rear mud guard.
Looking at the photos, one photo of 121 illustrates a crew member in what appears to be a lighter tan uniform. The other photos of 121 illustrate a crew with dark uniforms.
And sure enough, there IS a photo of a Tiger with two crew members with bleached feldmutze.

These are so bleached that this must have been intentional. According to the
Osprey Elite Series 34 Afrikakorps 1941-43:
The olive color of the cap quickly faded in the strong desert sun. Many soldiers deliberately bleached their headgear as a faded cap was the prestigious mark of the veteran campaigner, and a dark cap the mark of a 'new boy'. Interestingly, the caps contrast quite a bit with the uniforms in shade, the uniforms being much darker. My belief is that such caps on the Tiger crew were almost certainly an affectation.
I will add that the 501 photos do illustrate a lot of crew quite bundled up against the elements. Examination of photos of Italian, US, British and French soldiers show a lot of the same. It was NOT like Libya Summer 1942, but many modelers persist with this in spite of the photo evidence to the contrary.
But then again, hey, it's your model!