You are probably looking at the empty weights published by Grand Design. THEY ARE MEANINGLESS! Use the GVWR of the trailer (gross vehicle weight rating) and calculate 13% of that for loaded tongue weight. If you are looking at the Imagine 2400BH (unloaded weight 5,595), the GVWR is 7,495 and the loaded tongue weight will likely be around 970 lbs. "Max tow" capacities on tow vehicles are only secondary to their payload capacities. If you take the curb weight of the tow vehicle (preferably from the nearest CAT scales) and subtract the weight of passengers, gear, and 100 lbs. for a good weight-distributing hitch, you'll be surprised at how little you have left over for that loaded tongue weight. I have pulled a similar trailer with a 1/2-ton vehicle and would not do it again. The motor and transmission are important, too (as are the brakes), but I would pay more attention to payload first, and then the rest.
Rob