One more thing regarding the lift systems:
The most common are the cable driven types with telescoping support posts such as Coleman and Starcraft. Some brands, such as my current Palomino, have external arms with spring assist either inside the arms where they fold or under the trailer itself like mine. While not as nice looking as the internal cable driven arms and needing a little more manpower to lift the roof, I prefer the external spring assist arms over the cable driven type because the external arms are more reliable and need no maintenance or adjustments. Cable systems can sometimes need adjustment and if a cable breaks, can be expensive and difficult to replace.