I bought a rather odd tent that was on closeout, a Big Agness Super Scout. The vestibule area is about the same length as the interior of the tent, and even wider. Great for my kayaking trips where I have extra kayak gear like my dry suit, pfd, etc. A "floor" for that vestibule would be sizeable. I was sitting inside the tent body when I took the first photo.
When I bought it, in part I was thinking that this vestibule was so big I could sit in it during rainy weather instead of putting up a tarp. The door is zipped closed in this photo, the door is the two zippers on the side between the two taller poles.
I think they made very few of these tents, did not stay on the market very long. Theoretically you use two trekking poles for it, but I cut two poles to use instead.