Ive been using a rooftop tent for the last 6 years - a hannibal, made in South Africa. Brilliant and easy. I too have a room underneath and do not bother to set it up.
My tent is mounted on what I now drive - a GU series 4 wagon. Its been on my 79 ute on top of the canopy, my troopie, rear opening, my short wheel base BJ40, also rearward facing, my falcon ute rear facing on a canopy, my 95 series prado, also rear facing and now its on the patrol.
I own an awning from ARB which opens up to the side... mush more useful than having the rooftop tent open that way.
enjoy your tent. Ive spent more than 350 nights out in mine and I love it... the camper trailer is literally brand new this week so I will reserve comment on which is better
cheers
Alby