Magnavox makes a great LCD TV that works on 12v. The units come with the converter in the cord. I just went to RadioShack and got their cigerette plug and adapter kit. It is then just a matter of selecting the right adapter.
We have two of these TV's in our Airstream 345. The down side is that the ones we have are NOT digital. We will have to get a converter box for when we use the roof antenna. Most of the time we use the portable satalite dish with our Direct TV.
I'm sure that they make the same type of unit with the digital tuner.
Rob