'67/'68 GT thru Sovereign
baths are similar. The '68GT pocket door simply butts up to the melamine face of the closet in the bath. There's no jamb, stop, or casing.
On the OverLander, there may be a strip of wood trim to cover the transition from the melamine face to the face of the forward adjoining closet. It could stand proud of the wall enough to mimic a jamb, and cover the door to wall gap. On the GT, there's a 90 degree 1/2” wood corner trim from floor to ceiling, as that's where the kitchen bulkhead is. In the photo, the upper half has been replaced with 1/2” aluminum angle.
There isn't anything vertical that the door actually nests into when it is closed. There was a toe-stubbing 1-1/2” U-shaped plastic that was mounted to the floor next to the melamine closet that was intended to hold the door bottom in place when closed. I didn't keep it, it wasn't necessary, looked ugly and cheap.
Sorry these photos don't help much with the explanation. I permanently removed the overlaid bath closet door, I didn't agree with its swing. Cased the opening with ash, lined it with aromatic cedar, and made a his/hers clothes bin in bottom.
Alignment-wise, things were originally VERY out of square-level-plumb. I think someone could figure a number of ways to improve it. The upper glide rail and nylon rollers are marginal in quality and function. My nylon rollers were no longer round, required truing. In retrospect, I'd start with a better quality glide rail, and not follow Airstream's chintzy design.
The pocket can be troublesome. With humidity over the years, the bath wall, which is faced with melamine on the bath side, but unsealed plywood inside the bulkhead, warps/bows into the pocket, causing interference with door. My original door was seized into the pocket. Making a thinner door was part of the best solution for me.
Here's a link to my pocket door adventure, with better explanation.