Although your vehicle is rated for up to 3500 lbs. that does not mean that the brakes are up to having that much added weight and stopping the car soon enough or hold up on a steep mountain downgrade. I would look for something weighing around 1500 lbs. and planning to add 500 lbs. of gear, food, water, etc. when traveling.
Check the actual measurements for each sleeping berth. Often a berth is only long enough for someone 5'6" or shorter.
Your other options include getting a different vehicle or renting a Class C motorhome when and as needed.