Best models in my opinion are the Avtex brand, but they are pretty pricey. Just for the 16 Inch model your looking at roughly £300, but it is a very good TV, huge viewing angle and one button set up.
Have a look on bog standard domestic portables for the DC input socket and check to see if its 12v - if it is, ( and its very likely that it is), you can simply get a connector to fit that socket on the TV (it'll be one of those round ones which are easy to get hold of at Maplin, RS or Farnell) and just make a lead up to connect it to the DC supply in your caravan or tent, or even directly across the leisure battery.
The bits will cost you coppers and you can buy a bog standard TV also for cherrybobs.
You could if you wanted spend the national debt of a small 3rd world republic on a branded one specialising in this sort of thing - maybe beginning with 'A'
I bought the Finlux - excellent value. (See Mick and Tina's post)
Just one thought - why do you need a 26 inch TV in the van - It is rather large. 20/22 inch is probably all you need. Don't forget the weight on the bracket (If it's going on a wall)
We have the Avtex 18" having come from a lovely 15" SONY we ran on an inverter, via a couple of MobileTVs.
The latter failed out of warrantee and the SONY would not fit in the dedicated carousel built into this van.
The Avtex is a nice set, but its failing for us is the appalling length of time it takes to auto tune. Crazy IMO for a set targeted at use in caravans and mobile homes which by definition move location.
Another "weakness" is that its built in satellite decoder is a generic one. Here in the UK market a Freesat unit that brings a decent EPG would be much more practical.
Its low power consumption is good, as are its viewing angles; colour balance relative to the SONY is IMO poor.
The Mobile TV; the van's original fit failed and was replaced under warranty, only for that to fail just out of warranty. Whilst they worked they were good TVs on every count.
The Avtex TV's are nice bits of kit, however, i always feel that its the usual priced high because its marketed as a 12v TV when you can get some cracking deals out their for a fraction of the cost, i.e. in many cases 2 in fact lol
------------- Regards
Mick + Tina
Good Bye To Our Abbey Spectrum 520, Hello To Our Elddis Crusader Cyclone