I am partial to the GM Duramax diesel trucks
Model year 2006 - beginning of year 2007, has a "D" in the 8th position of the serial nbr (RPO code LBZ) are the years with the least emission controls, and the most fixes that GM has incorporated into their Duramax diesel line (both GMC & Chevy). Model years 04.5 / 05 (has a 2 in pos 8) were the LLY engines and some of them overheat/run hot (we have one of those but it is paid for and I am fixing it). The LBZ's have a 33% bigger radiator, and the 32 bitBosch computer that the earlier trucksdon't have. The 07.5's brought on the DPF (diesel particulate filter) and mileagecan drop at times significantly due to the regen process.
There are significant nbrs of low mileage LBZ trucks on the market right now. There is a crew cab one over in Maryland with only 7000 miles on it and one in Kentucky I had found for my bro-in-law with 5K, no mods, always kept in a garage.
Look on www.autotrader.com
GM is having issues with the 2011 diesel due to the urea (DES) fluid freezing in the colder areas of our continent (Canada, upper US). They don't quite have it worked out yet.
A well taken care of LBZ truck will do exactly what you need without breaking the bank even with the cost of diesel going up.If it was me, I would go for a crewcab short bed, (that is what we have).Thelong wheel base (but not as long as an 8 ft bed)makes pulling a trailer super easy, but if you don't need the extra doors, there are some extended cab long bed trucks on the market.
Keep in mind tho, that the short bed trucks (crewcab or extended) only have a 26 gallon tank.
We pulled a 28 ft Salem travel trailer and last fall just got a 30 Cruiser TT andours handles it just very well.