Cathy, you can do just about anything you want. When I built my tiny travel trailer, I made it modular so I could do many things with it. The beds can be made into an almost queen size (59X73") or two cots (22x73") or anything in-between. Please note that a 22" wide bed is the very smallest advisable; however, it allows for a 15" walkway between beds, which the smallest possible to still be able to walk comfortably and be able to turn around in the aisle. A 22" cot is the width of the beds on submarines. Pics, below..."

My trailer is 5' wide. If you are going to make two beds that will always stay as two beds, I would most likely build platforms (depending on door access) and either make the top of the platforms removable or hinged or put drawers underneath for easy access or do a little of each. Please recognize that, regardless of what style bed you do, you will need to consider your exit plan...: Where is the door? If the door is in the middle of the back or front, the center aisle is a perfect solution. If the door is on one or both sides, maybe not. If the door is at the side of the beds, I would not put a platform in that area; but rather, have that area of the bed be either collapsible or removable, or have the entire bed on the floor, for obvious reasons. (I have a door in the center of the back plus a door on the side; so, the bottom 30" of my bed platforms are removable.)
You could also put one cot in the Durango and one bed in the trailer, if you can trust your son to sleep alone. Or, you could have a tent on the side with a cot in it and sleep with your window partially open on that side. There are tents that can be erected in less than a minute! Or, you could go for tent with a little porch-like flap area and have an outside "living room" between the tent and the trailer. ...So many ways to do what you want.....
You just have to think and dream about what you want and it is achievable. My favorite thing to do is to go to bed thinking about how to do something and let my brain work while I sleep. Usually, when I awake in the morning, I have the answer.
Best Wishes!