What would be the min size truck to tow 24 foot enclosed?

[art leong]

I use an F550 conversion (had it to tow my 48' LQ trailer)to tow my 24' featherlite. I was going to sell it and get a smaller pickup to save money on mileage. Looked at what I could get for it as compared to the price of a smaller truck. Decided to keep it. I have since replaced the transmission (went for the money $5000). Now I'll keep the truck till it stops running (should get at least another 200,000 miles towing).
I only get 10 mpg towing and won't go much over 65 mph due to the 4.88 gears. But when I go to stop it stops, when a tractor trailer or bus blows by me on a highway I don't know they are there till I see them. I don't have any sway bars or an equalizer hitch.
It's 10 mpg but the peace of mind is priceless.