While I agree that having an inverter is convenient for many reasons, I can also see how not having to use one to power a TV is also convenient. In my case I have an inverter mounted centrally in my TT, it is close enough to use it with my main TV. If I wanted to move that TV outside and plug it in I would need to run an extension cord out, likewise if I were to move it to bedroom. It would be much easier to just wire in a 12v plug to the areas I intend to move it to. Of course there are ways to install an inverter that will power the 110v outlets throughout the TT but that gets a little more complicated and expensive which is something the OP indicated he was trying to avoid. Could also wire in multiple inverters but again gets more expensive.
I also agree that a Blu-Ray that is capable of playing both formats is more versatile. Just speculating on how the OP plans on using this TV, I can see how a built-in DVD player works for probably 90-95% of how he intends to use it. The set with a built-in DVD can be moved by itself outside for instance to watch a DVD. Don't have to also move, hook up, and power a Blu-Ray player. Seeing as to how he has said he has tons of DVD's already it sounds like that is mostly what he intends to play. The set with the built-in DVD can also have a Blu-Ray player plugged into it if desired. Seeing as to how the Insignia's that have been linked are cheaper than some of the other TV's alone even adding a cheap Blu-Ray would have the cost less than many of the other TV's suggested. That is the same thinking I used when I bought the one for my TT bedroom. I figured I could move it outside and watch either TV or a movie on DVD. I was able to pick up the 24" model for about $120 on one their deals of the day. So for that price it was a very economical way to accomplish what I wanted which sounds similar to what OP is doing. The TV has performed well. I was happy enough with it that I also bought 3 more without the DVD players to use at my house (again on a deal of the day). I put 2 on my patio and one in my kitchen. The one in the kitchen gets daily use and has been great. I also have other TV's, 3 Samsungs, 1 Sharp, 1 Toshiba and a Dynex on my office wall. The only drawback with the Insignias that I have found is that the volume can be a little low. In a TT setting that is not a problem though.