I love this design! I've actually seen something like that in person long ago and I remember that I loved the idea then. I still love it now.
Looks really practical and easy to work with. I also love the elevated view point.
But my dog would hate it as he would not be able to climb in or get out whenever he wanted. But the elevated view point will be very good for barking up the area ;)
It would be really cool and fun to try but you're right about the dog. I'm sure that a cat could climb the ladder.
It's a classical impasse because the dogs would love camping but wouldn't be able to climb up to the sleeping quarters and cats could easily climb up there even without the ladder (which I can prove with countless nail-scratches on my car already) but they tend to be attached to the place where they live and would rather not come along camping and would probably find it quite stressful.