Re: swarm call, too late
I don't know if this would have worked for you--but twice I got bees out of cinder block wall of garages by using smoke and banging on the wall. First time was at my son's house and the bees had moved in a day or two before I did this. There was only one opening into the wall on both occasions. Lots of smoke and banging on the wall.
First time, they all came out at one time and swarmed and clustered into a bush 15 feet away. I clipped the branch and put it into a hive and took them home. I had to retrieve them once more after I got home. They became one of my best hives which I still have.
Second time, they flew all over the place and as it got dark I plugged hole and left a nuk with drawn frame next to wall. Next day I went and put a one way cone and left box, not expecting ever to get bees from it. The homeowner (co-worker) told me a week later there are bees in the box so I went for them. No queen but they'd drawn out another frame. Took them home and combined with another hive.
I think the one entrance was key in both these situations. Not sure if it'd work in a trailer. They really disliked the banging on the wall.
Pleasant words are a honeycomb, sweet to the soul and healing to the bones. Prvb 16:24
March 2010; +/- 30 hives, TF