Only if you have a truck camper do you have any slide-in specificity. To the unwashed, a camper can be any kind of 'camping' vehicle, whether it be a pop-top tent trailer with wheel barrow sized wheels, or a chassis mount 'camper' as shown above.
If others are puzzled by our Truck Camper designation, which they are; to wit the pop-top camper folks who chime in anytime the term camper is used by us, assuming it's what they have, then so be it. That's why I'm up for a new term for the off road version of the truck camper...you guessed it: XTC.
regards, as always, jefe