I am with Smike. You try find a comparable enclosed trailer and load it up and go for a test drive. If it feels acceptable, buy what work for you. Although watch out for overweight as I'd think you don't want to lose the warranty (if any). Even though how can they find out? Just bring the truck in and not make it obvious.
In Illinois, they don't care about my truck's tow rating, but they will bust my ass if I'm over the weight class I plated/registered my truck for. I almost got fined $3000 for running a 8,000lbs plate (Truck B) 3 years ago so I upgraded to 12,000lbs which means I can have up to 12,000lbs on my truck by itself plus towing.
Well, that made me to think, I already went over a little!
Although I had ~300 gallons of fuel in back of my truck at ~2400lbs.