It would be difficult to mistake a light brown or tan shirt for this jacket. Your assumption isn’t so safe.

Why would that be difficult. Early in the morning, probably just awake with the light of the sun, anything is possible, right?
Isn't it your argument that the color of CE 162 could appear different depending on the conditions it is seen?
And it doesn't even matter if my assumption is safe or not. Even if Oswald did not wear a jacket to work on Friday morning, CE 163 was still found at the TSBD, and Oswald left the TSBD on Friday without wearing a jacket.
So, I ask again, what's your point?