It's a very close call, man. If you're doing "the chief" then do the damage. It'll be ok, I promise.
I personally like it being clean, though, and think there is no way that will ever not be legit.
As for the paints. If you can find some way to get a silver, shiny house paint in a few thin coats, then go over it with the green, that way when the paint wears off it will be metallic underneath? But other than that, after this long of experimenting and finagling, I think it's time to commit. Sometimes we have to make sacrifices in life in order to move forward. We may not get it exactly right the exact way we think we need, but I promise you this, sorry that foam work underneath, no matter how gi go about it, it's going to look absolutely fantastic. I've never seen foam work like that.
I think you should paint the thing, man. You need to paint it.
Anyone else feel this way?!
EDIT: In case I sounded a little wishy washy about the damage: your re-creating the chief. Do the damage.