I posted a similar thread in the truckcamper forum, as my wife and I are not sure if we want a truck/camper rig or a toy hauler. We are getting close to retirement and thinking of travelling with our...
I know two people W/TH using 1/2 tons. They both wish they had at least a 3/4 diesel. Doesn't matter if you buy a camper or a trailer, more truck is needed for what you want to do. None of them get good mileage towing, but diesel will do better than gas.
When you drive in the mountains, there is no comparison between gas and diesel. Especially on steep downhills, the diesel shines with an exhaust brake.
Take your time and enjoy putting the pieces together.