I've been touring for many decades now, mostly with motorised caravans, but I did try touring caravans a couple of times. They are more spacious and can be left set up on site, but motorised caravans give much more freedom, allowing you to stay at a different site each night when touring an unexplored area.
Over the years I've had many 'Vans, and it's always been a compromise between site comforts and driveablity with a compact vehicle that can be easily parked etc.
The largest I've used was the Talbot Camelot, and the smallest was the Escort Elba, based on a Ford Escort van !
I've carried out many mods, and even did a complete DIY conversion of one, ('Helga', my VW T3), as detailed in these pages.