Will the shade of green just blend into the trees? It's approaching 24 hours missing...
I imagine that it will not help.
Depending on the area, however, the woods can be so thick that the color of shirt would probably not matter outside of a clear cut area or forestry road.
The fact that one of helicopter crews had difficulty seeing the ground implied truly thick, east Texas woods.
At the same time, one of the farms in the area had a 360 degree / google feature. At least in that part of the area woods seemed to open up alot.
As a side note, the area as a whole is probably right on edge where the east Texas "Piney Woods" start to turn into the Texas plains. Though people often associate Texas with dry plains (and rightfully so), the eastern say, 1/6 of the state is very heavily forested.
My father was an infantry soldier in Vietnam and once mentioned to me that the east Texas river bottoms in summer reminded him of his time there.
I hope the helicopters have sensitive flirs (Foward Looking Infra Red System- or something like that). Like everything, the technology has gotten better, smaller and less expensive. As a result, super capable IR systems that were once only for esoteric military aircraft, might be used on police helicopters now.