All is looking Really Terrific! Love the trailer and fuel cart! As for hangar wall material if you are looking for plastic I will say that Plastruct makes a myriad of styrene sheet that is deeply grooved to represent wood planks. and could be painted to look like wood in the usual manner. Also look into G Gauge train stuff. Some of the materials are done in 1/32nd scale as the gauge varies widely in scale. If you are looking for real wood I am sure it is out there in Model RR accessories, just can't remember who makes it.
IHTH,
RAGIII