I'm adding a basement bathroom and am working with limited space.

Because of that, I've ruled out a conventional bathroom door, as everyone
in the family (other than grandkids) would have to duck once the header
and trim were in place.

So, I'm considering a pocket door. But again...space is a consideration.
.....
So, my question is: has anyone installed a "custom-fit" pocket door, and
do you have to be Bob Vila to pull it off? Is it worth the hassle? Or
should I go with bi-fold doors (the only other option)?

All the pocket doors I've looked at run on overhead rails, which means
the assembly takes up *MORE* overhead space than a regular door,
because you have to hide the track.
Just case the sides of the doorway normally, and leave out the
header. Build up the joist flush with the walls on either side,
so you can add trim (bottom edge flush with the bottom of the
joist) and fill all the cracks and seams that would normally be
covered by the casing with wood-filler, and paint.