In this article I want to highlight only the possibility to sleep in the SUV, because a bigger focus is beyond the scope of a single article. There are so many options that it is just to much to write about: there are still the other vehicle formats, vans, pickups, trucks, sleeping in a roof tent, folding roofs, pop-up roofs, caravan fittings, Trailer, simple tents, which vehicle choice as such, and much more..
Even with the off-road-vehicle choice you will define a lot about the available space.
Depending on the vehicle length and the square of the front seats must be taken in fitting, ie, the seats must be folded to the front / rear to get a decent sleep platform.
But the decision will not be taken off you, it's finally about how will you travel. You do not end up building what others would. All extensions are unique - not expected that others would like to build like you did or like you plan to build.
Buschtaxi Forum - J7 Innenausbau
ih8mud-Forum Sleeping Setups
foro4x4-Forum Ausbau Beispiele
Expeditionsportal 4x4 Ausbau
forum4x4 Sleeping Plattforms
Here some more generic ideas about how other camps look linke:
Offroad Forum - zeigt eure Behausung
Expeditionsportal Campsite Pictures
ih8mud-Forum Expo Builds
And here an Expeditionsportal Thread about drawers and boxes:
Expeditionsportal Schubladen Systeme
I hope you will got some nice ideas and hints!