I've seen a few episodes of those shows... The ones I've seen have been way expensive, and while they look nice, they look like functional disasters on wheels!
I can't imagine constantly subjecting them to 60+mph winds and the rigors of road life without constantly losing roof panels and/or shingles. I even commented to my wife one time that the couple on one particular episode who had a compact car and a $30,000 budget could afford our truck and camper combo (30-foot Jayco with a V-10 crew-cab Super Duty) for the same price, and would not have to worry about what to do with the human waste or how they were going to heat it comfortably!