Looking at the floorplan of that unit, it appears the floor only extends to the front of the long bench at the back of the U. It's seat is actually the edge of the camper that extends over the top of the pickup bed.
There's only 4 ft. of width to work with at the floor level - the distance between the wheel wells on a standard pickup.
That's probably why the manufacturer chose to make the dinette U-shaped. If you make it into a booth you'll only have legroom on the two short sections that extend ahead of the existing bench seat.
The only way to fit a booth dinette would be to raise the dinette floor to the level of the existing seats, then build the new dinette on top of it. That's what they do with slideout campers, but the rise is partially disguised because the camper floor is already raised over an underfloor storage area.