The very pristene mid-war one I have in my collection is about panzer grey (if you have a bluer bottle in your rack that would be better).
My well used late-war version is very faded from sun and salt water--it's mostly about dark gull grey with light ghost grey upper surfaces.
I've seen copies in museums that were close to thin British Sky over khaki. Others that were a decent match for feldblau, or French field blue (or halfway in between).
Amtrak drivers & crew should be in OD HBT, but recall that "looking salty" was very common, so crews would drag their OD in nets behind the ships to saltwater fade them. Then, operations tempo made mix-n-match mostly common. too.
USN Landing Craft were usually manned with Sailors, and they usually turned to in dungarees, with the kapok and a helmet being the only addition. Army personnel, from the photos I've seen wore OD HBT, sometimes with boat shoes rather than issue combat shoes (which would be brown, USN non-aviation personnel had black leather shoes).
Now, if it was wet out, or in colder operations, the Sailors manning LC could be wearing the rain parka, or a deck jacket, even full foul-weather gear.