I guess the newer TVs from WALMART must be going back to the so called BRICK idea for power. I know many years back they were very common to see... All of the TV's I have got and looked at from WALMART in recent time all seem to have a 120VAC cord that plugs into a socket on the TV...
I would definitely look for the BRICK or ask about that before buying one. That is definitely a great idea. You can make up a DC adapter cord with parts from RADIO SHACK...
I had an older 19-inch TV (can't remember the brand now) that had the brick and said it ts output was 15VDC that plugged into the back of the TV. It worked just fine off of the 12.3-14.4VDC I was running in my POPUP coming from the on-board converter/charger setup. Just don't get worried if you see 15VDC-probably even 17VDC which I have seen before too. IT should work just fine off the RV trailer Battery system setup. Some of us have stand alone DVD players however which needs 120VAC to work which you won't be able to use without shore power. Maybe you can find a TV set that has a DVD player built-in.
Roy Ken
Roy Ken