We bought a used 2008 Dodge Dakota 4x4 Quad Cab expressly due to it being "4-down" capable.
Have towed it on 4 trips thus far and works great. Its weight is under 5k lbs, which is under our tow limit (plus no tongue weight.
I use a ready-brake system and installed an under the bed 42" LED light bar on the back and hooked that up to a 4-flat wiring harness that plugs into the RV. That LED light bar is VERY BRIGHT and works well for running lights, brake lights, and turn signals.
If I were looking at BRAND NEW trucks I would consider The GMC/Chevrolet Canyon twins, OR a new Supercab F-150, which is surprising light for a full-size pickup.
Good luck!