Here's my solution for the lack of cupboard space in my tent trailer (Bonair 800). There was this big piece of aluminum covering the wheel and I could hardly put my pots and pans. Worse, I lost articles to the rear and would cut my hand trying to recover them.
The removal of this large piece of aluminum gave me a least an additional 3 inches in the front and 2 inches on each side, just enough to finally close the door.
By adding a small shelf on top, it gave me the extra space to store small items.