I'm a ways off from doing any conversion of my own (have to get a functional Rover first), but it's always nice to have a direction to work towards.
The X-Panda's seemed like an interesting concept, although I would have put the "hinge" at the front so that the highest point would have been in the cargo section (standing room for cooking and stuff) and the structure would have been less likely to take flight on the road if it wasn't properly secured.
Either way, it would take a good amount of structure to pull off securely, and I'm not sure how much weight I want up there on a permanent basis.
The Carawagon Safari also looks interesting, but I'm not sure how much I want to hack up the body to do it. It's fun to look at all of the different solutions to the same need, and then pick and choose what suits your needs.