This layout will show you what I did on ours.  It is a 7' short wall so if you were to draw a vertical line up from the right, that would approximate your square.

In that area to the left (front wall ) is a bench seat with cabinets below it, on the right wall is a sink (with cabinet above) next to the bench, a tall refrigerator next to it.  I believe it is a 7.3 cf with a freezer.  You can do a smaller one and have a counter on top of it or additional cabinets. In front of the bench seat is a removable post table.

You didn't specifically say if your trailer was a gooseneck or not, but if it is, we have a 60x72" bed with cabinets along both sides and in the nose of the trailer as shown.

Make a scale layout and use cardboard cutouts in the actual trailer before you commit to a final layout. Everything is available to do what you want, just verify the sizes of all components and use those in your layout.