If your trailer does not have the backing built into the wall you might want to add a 1 -inch back board yourself secured in its four corners hopefull into some wood or metal wall studs etc. You can also use what they call MOLLY BOLTS as well.
Then you can add your swivel mount directly to the heavy wood back board..
Might look something like this google image...
Just be aware the trailer walls are very thin 1/4-inch material and will not support a large wood screw. It will simply pull out on you...
Some trailer have a sticker label on the wall saying you can use this area to add the swivel mounts.. Everytime I see one of those I don't know how big of area they are talking about. Maybe you can tap on the wal to determine this...
The LED/LCD Flat screen TV's do not weigh very much...
Roy Ken