Hunter Compact I looked at was the same. I thought it was a novel/good idea, as any water that
leaks along the sides doesn't immediately reach the wood in the floor. Its really not needed anyway, as the frame is inboard and the door is in the center rear. Side doors on traditional trailers means floor has to extend to the side on at least the door side.
I guess there is nothing supporting the side walls structurally, I haven't really thought about that. Does the frame have some cross pieces extending to the side walls? I didn't look at the Hunter that close.