Dennis, as mentioned many TV sets are using the wall brick instead of a std 120vac cord. This will work to your advantage, all you have to do is buy a cigarette lighter cord with the correct plug and you're set to go. You said you are changing out from whatever and I'll bet there is a antenna connector with a 12vdc socket. If there is one, nothing else is needed for OTA reception.
If you don't have a 12vdc socket they are really easy to install. Another feature is the flat panel uses less power and eliminating either an inverter or the need to run the genny.
The mounting is an added expense but if your clever it's easy.