If I were looking for a good, strong dependable good tow rig I would pick a ford Diesel. ford has been the number one selling truck, for many years, which means literally there are millions more out there than any other pickup, This also drives the price down to reasonable, because a lot of times, guys sell a ford and buy another one, (yes, they are that good) over and over.
diesels are not like car engines, you need a good mechanic to find a good one, ford also uses a real diesel power plant the one complaint if any is they tend to be a bit underpowered uphill towing heavy loads, however a knowledgeable owner can add a banks turbo, larger exhaust, have the fuel pump worked on by a GOOD MECHANIC (I AM NOT A BIG FAN OF POWER CHIPS) AND ford has a 5 speed overdrive transmission perfect for much heavier loads than your trailer.
There are killer deals on older fords in the 5 to 10 grand range. If your price range is higher, you can get a really , really nice ford, that will move your trailer perfect. I suggest a 3/4 ton, it is made with truck axles and bearings, not light duty half ton car parts. fuel mileage towing, would be excellent, and the banks turbo and exhaust may be more than you need,
Go find one you like, hook up the trailer and take it for a 40 minute test drive (that's what I would do) find a nice long steep upgrade, and if the pickup is still doing the same speed at the top, its a winner. There has been many a bar room discussion between the five speed, and the six speed. A six gear, is another overdrive gear (both are automatics) the five speed is plenty beefy, ifs strong, does not need a sixth, and because a sixth gear is not squeezed in limited space, this makes the transmission strong enough. And as a added bonus is a lot harder to blow up than the six speed, and best of all, is about 1,000 to 1,500 hundred dollars cheaper to rebuild.
There is a reason that some guys have bought ford diesels over and over, some old timers have bought six or more best of luck, that's what I know about ford.