Boxtruck rear door skinning

So I made a skin for the boxvan and it works normally.

But then I open the rear doors and it looks like this:
I think its kind of ugly and unrealistic so I would like for the inside of the doors to not be part of the skin. Would that be possible?

 

Here's a screenshot of the skin:

 

Wait so the doors are not meant to be skinned?

 

I think they can be skinned, but the front and rear of the doors arn't separated.

 

Oh ok.