You will probably find the slim low profile pinch type receptacles being used in your trailer.
These do not take up much room and are very popular among the RV manufacturers installing on flat surfaces..
Being a pinch type the wires are pushed in a cutting jaw which creases the copper wire and makes them very easy to break if bent.
Also when installed they do not usually leave you any room to replace them making you have to install a junction box first so you can gain enough wire to install a new receptacle.
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If I have room I will replace all of mine with the regular house type 120VAC receptacles with a PVC electrical box...
Roy Ken