As was mentioned previously the Truck for a 25-30 foot trailer will have to be a 2500 series, half ton may work with a newer lightweight trailer, but older ones are heavier.
As far as the Bob Wells comparison, you could on $6000 buy a van, build out a bed, basic storage and add minimal cooking facilities, but has your fiance thought that through, especially living in your area with no rooftop AC. And she would also need to consider buckets instead of toilets.
If you have to split that $6k between truck and camper or Class C or building a conversion, your in for a tough first few months till you work the bugs out of what you buy. There are some tougher aspects of what he does, and a lot of folks who won't choose to live that way.
