I see folks are mentioning mileage with the bigger trailers, so thought I'd mention my Five Wide mileage. I started out with a regular Five Wide, pulled by an offroad Xterra six-speed. I got 18-20 miles per gallon, with or without the trailer which weighed 950 pounds dry. By and by, I sold the trailer and got the off-road Five Wide model which weighs 1450 dry. With all my stuff, it probably weighs close to 1700 pounds to include 6 gallons of water, 52 quart cooler full, spare tire, Action Packer full of stuff, galley full of stuff, etc. Well, I still don't notice a difference. It could have lost 1 or 2 miles per gallon going uphill, but not so I could notice because if I go up the mountains, I go down again. I don't think I can complain. I also have an awning sitting up there and a roof basket. And a few pounds in the back of the Xterra. The Xterra is just as high as the trailer, so expect that helps.
I cannot stand up in it, but the dog and I have had lots of fun.