For a dedicated TV, don't even consider a diesel. Way too many maintenance issues and diesels need to be run....a lot. If you don't run them, bad things happen. Heck, bad things happen to diesels even when run a lot. Gas is cheaper, oil changes are cheaper, and if you run them with non-ethanol, you can let them sit for long periods without any problems. A good Ford F-250 with any gas engine from 2005 - up, will do you fine. Same with the F-150's if set up to tow.
2008 F-250 4X4 Lariat V-10
2002 Airstream Classic 30' w/SO #2074
2007 Kubota 900 RTV
1996 Ford Bronco
2007 Lincoln LT