Each trailer is different I put a large screen in the area where the old tube TV was, I made a door to hold the new flat screen 1 continous hinge. and I also have a storage for DVD's and CD's behind it the picture dont show those but you get the idea.
Good luck on your new project, also cutting the face frame on the cabinet might not be a good idea they use screws to hold the face frame together the Kreg jig I believe.