MotorHome Magazine puts out a comprehensive list of flat towable vehicles in their annual Dinghy Towing Guide. You can download each year HERE.
In our opinion, the Jeep Wranglers of any year or model are the easiest to setup and tow. Not only are they cool, but they can go anywhere and there is nothing you “have” to do to tow it. Though there are many great vehicles that can be towed, the Jeeps follow the K.I.S.S. model.
Like any flat towable vehicle, you have to install brackets for the towbar and a breakaway switch, but that is common to all vehicles.