I need a custom wooden tarpaper tunnel environment.

http://lotgk.files.wordpress.com/2008/02/idorawildcat.jpg

I need a custom environment to make the default wooden tunnel look like old dark tar paper on the outside and the inside. Like what is covering the top pf that coasters tunnel, but a little darker. I also need the tunnel to be a little smaller in size than the default wooden tunnel. I need to have the train barely show up when it is in the dark tunnel.
I will donate 5,000 points to whoever does this for me. I have a wooden seaside coaster that dives under the main boardwalk and needs to have a long and dark tunneled prelift.

Here is the coaster that I need the special tunnels for.

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