I don't recall who is/are the mfr/s and I really don't think they are US approved. The beige camper has the Rover wheels on it, so it must be of an English settlement. I really think these are from South America mfrs.
Sorry I can't be more helpful than that.
I can understand the minimum/maximum width as I have similar requirements for storing.
Gate post to post is 78". There is an ac unit just inside the house post.
I have a plan for extending the sleep area. With the angled pop top, make it rotate all the way over when you need another or 2 sleeping space. This idea comes from the Flip-Pac design. Use the tilt for standing room and then extend another subframe which holds a bed. That way, you can have the pop top short of the full length of the roof. The full flip would use the top of the camper as a base support and if necessary, add supporting bars to the tongue. If another bed is needed, add a platform where you stand. It doesn't need to be wider than 35" so there will still be some standing room. Several Flippac owners have done this with a cot setup.
If you plan to place an awning and side panels on the exterior, why not look at adding sliders to those cabinets which have access from the outside. Slide the cabinet outward like a slide-out. This provides much more interior room and the cabinet is still weather protected. You can add rubber trim to keep insulate and keep the bugs out when its opened. Add a small doorway to the cabinet to gain access from the inside as well.
To maintain trailer stability when camping, add rigid stands right behind the tires like in the link from pcambell.