I like the Element and I know 3 people that had them. Biggest complaint was gas mileage. My friend had a early CRV and on road trips together, it was funny that our 02' Honda Odyssey van got better gas mileage (23.9 last trip, in winter with snow tires) and the new Odyssey does better.
None took them off road. Seems the 3" lift would be well worth it.
Anyways, there is a Honda tent option for rear hatch as well as a "cabana".
Cabana - http://www.handa-accessories.com/element/tentpoles.jpg
It seems to me, removing the rear seats and sleeping on the floor (onto the tailgate) would be more comfortable than those fold down seats, but perhaps they are OK??
Or a roof top tent perhaps - http://www.autohomeus.com/gallery/honda.php