I used a studfinder to map out the area behind the wall. I realized the wall was solid in some places, but I also realized it was only one inch thick.
I then got a thick piece of hardwood, and mounted that to the wall, hitting as many wall points as I could. I screwed in the screws to the one inch depth after drilling a pilot hole, then backed then out and cut the tip off the screws and screwed them in again.
I mounted the swing arm onto the hardwood with short very robust screws, I think about 1/4 inch thick. I put a piece of material behind the swing arm mount, and when travelling the TV is pushed against the mounting plate, and the material comes over the top and from under the bottom, and velcro strips hold it all tight.