As per the previous posts it is important to know your true tongue weight.
We decided to Rent a camper similar to what we were going to buy before we spent the big bucks. It allowed us to check our the floor plan and get a feel for towing one of these barns down the road.
In a week or so you get the feel for the floor plan you selected, getting 10 mpg, traveling 55 to 65 mph, parking the beast and most important you can drive to the CAT scales and check the weight on each axel. You will find that "dry" numbers mean very little and loaded for the road weight adds up very fast.
Good Luck