I have a sliding bathroom door, and I think it’s brilliant for a truck camper.
Our camper was already a private space and the camper bathrooms are relatively small. We don’t always close ourselves in there by closing that door and it was always in the way on all our previous campers.
Mine is a Northern Lite, its pretty simple how it’s mounted, maybe look at one and see if you could do a little custom conversion. It’s surface mounted, not a true “pocket door” that goes into the wall. If there’s space to slide the door over I think one could be retrofitted.