I have a Carefree Add-a-room. It’s a leftover from my conversion van. It does require that you have an awning. the “front” part slides in the groove at the bottom of the awning and there are two telescoping poles that support the sides. It has screen windows that zip open and a door. It seems like the same fabric that a pop up camper would have. I think you could adapt it to work with a bag awning. Google “Carefree add a room” and you can get an idea.
The downside is that it is kinda big and heavy and has 2 poles that you would have to find space for.
I don’t use mine and would be willing to sell it if you are interested. I’m near Harpers Ferry WV