While I'd love to improve my fuel efficiency, this takes it a little too far in the direction from "most of the comforts of home" to "no comforts of home". There has been a real move toward fuel efficiency in some categories of motorhome in recent years. Several really nice models are available that are built on the Sprinter chassis, which gets 14-22 MPG if you're not in a hurry. There's class B (van-like), class C (cutaway van chassis with a boxy house and cabover), and even a few class A (has a bus-like body that covers the whole chassis and usually provides the most living space) models. And, I've started looking at replacing my big diesel V8 F250 with a newish Ford EcoBoost 3.5 liter V6 F150; similar towing capacity, much better fuel efficiency (though towing a whole house will drop the efficiency by a lot).
What I'm trying to say is, while I love Tesla cars and a mobile lifestyle, this is goofy. A tent on the ground would be more comfortable, assuming you're camping in decent weather. A hybrid minivan or pickup with a topper would be smarter if you wanted to do minor conversions on a fuel-efficient vehicle to make it camp-friendly. I mean, I guess if you already have the Tesla and want to sleep in it every now and then, that's not so crazy (though I couldn't, as I'm 6' and can't sleep comfortably on my side).