Welcome and congrats on the new TT! We got a regular TV/DVD combo from best buy. It works great for us but we only operate when plugged in to electric. We don't dry camp. Not sure if you need something different if running off of batteries, gen set etc.
We watch TV from 115V and watch DVD on laptop computer. Having been in the TV business for years I have learned to get one appliance for one job and try not to combine functions. If you lose one, you lose them all if you have a combo. As far as 12V operation, I would get a small inverter to generate 115V from 12V to run the TV/DVD. You only need a couple hundred watts so a 500W or 1000W would work well and they are not expensive. I carry one in my truck all the time in case I need it.