Hey!
rooftop tenting is amazing =) The iKamper is a very special one, especially the size (1.90mx2.1m)in combination with the hard shell. Every other hard-shell is not bigger than (1.60mx2.10)...
Have a look at this HP: https://dachzeltnomaden.com/dachzelt-guide/
It's in German, but there are many useful informations... If you need an specific advice which tent fits to you, keep on asking π