This suggestion may not work, and I'm sure some might say it's the wrong thing to do, but I would try putting the dog's bed next to your bed.
The reason I suggest this has to do with my own experience with my miniature poodle (who is also named Marley!). My Marley is also a rescue -- although he didn't quite go through the trauma that yours did, still, this is his third home. The first night we got him home was a bit rocky; we told him to go to his bed and he went out and stood in the hallway! (That broke my heart). We eventually got him settled down next to our bed, though, and we went to sleep. I had to go to work the next day, and then meet some people at a cafe afterwards. My partner joined us at the cafe with Marley in tow. There was a whole group of people there, but Marley immediately came up to me, even though he hardly knew me. And the only thing I can think of is that by having us all sleep together in the same room, he knew that we were a "pack." We had a house guest later that week, but although Marley liked her, he didn't attach himself to her the way he did to us.
So, maybe this is all hogwash, but it's worth a try, anyway, I'd say.
But be patient. We were told that it takes 6 mos for an adult dog to adjust fully to a new home, and that was about right -- but we've noticed adjustments even since then. It does take time, but it is ever so worth it. Hang in there.