Since this is my first post, I can't post photos yet, so I'll tell you what we did on our Mallard 312 and then post the pics later.
I tried to determine if there was a stud in the wall, but I couldn't, so I gently removed the power outlet cover and then partially unscrewed the two screws so I could remove the receptacle. I was then able to use my smartphone camera and determined there was a backing plywood and no stud.
So I went to the hardware store and got some Hollow Wall Anchors by Everbilt (#6-32 x 1-1/2 in, rated to 85 lbs) and some Scotch double-sided 1" wide mounting tape. We purchased an Onn Tilting TV Wall Mount (32-47", 80 lb capacity) from Wal-Mart:
https://www.walmart.com/ip/ONN-Medium-Tilting-TV-Wall-Mount-For-32-47-TVs/51565662
I put two layers of double-sided mounting tape on the horizontal sections on the back side of the mount. I then centered the mount in the opening, just so it cleared the LED blue back light. I then drilled 4 holes through the backerboard, using the existing holes in the mount's vertical section as a guide.
I then removed the mount and set it aside. As directed by the wall-hanger instructions, I enlarged the 4 holes with a 5/16" drill bit. I then removed the screws from the wall anchors and inserted the anchors into the wall.
I then used the screws as guides through the holes in the mount and placed them in the wall so the screws went into the anchors and tightened them down.
Then I just followed the directions from the TV mount for installation on the TV. We bought a Visio 43", and it fits perfectly. We left it mounted for travel, and it did not move at all. We've gone on two trips since mounting the TV, and it still has not moved.
As soon as I'm approved to post pics, I will add them to this thread. Let me know if you have any questions in the meantime!