I was finally able to travel on the Bag Dorm car a few weeks ago on the Cardinal!
The Bag Dorm cars have 9 rooms (3 were occupied by crew - one for the car attendant, one for the coach attendant, and one for the cafe attendant). One room was stuffed with linens. This means of the 9 rooms, at most 5 rooms in the car could actually be available for revenue sale, maybe 6 if they could put the linens somewhere else. It looked like there is a linen closet by the door to the baggage area, although I'm not sure.
Just like the regular VL2 cars, it has 2 communal bathrooms and 1 shower for the whole car. The baggage area was hidden with a towel covering the window for most of the way, although for some stretches it was removed - allowing for a nice view out the back.
The service from the attendant was quite good as well. I was allowed to sit on the crew side of the cafe car for a good part of the trip.
Also wanted to mention the VL2 Cars seemed to handle the rough Buckingham Branch RR stretch quite well! While the ride in the Cafe car was quite rough through this section, it seemed much smoother when I returned to the room. Other than a slight delay and Flexible dining, I was quite satisfied with my ride on the Cardinal!