Yes and......... most manufacturers use white products, especially fiberglass panels because of rapid UV damage to the darker colours. Black and especially red colours are quickly affected by the sun's rays. The plastic in a FRP (fiberglass reinforced plastic) layup is the actual resin adding stiffness to the glass. This is easily damaged by the sun's UV spectrum. A colorant is added to the resin just before the layup is started. Depending on the colour, various amounts of sunlight will reflected.

In the manufacturing of boats, you will almost universally see white hulls. The marine environment is especially tough on fiberglass, not only are the boats constantly subjected to the direct sunlight, but a great amount of reflected sunlight as well.

In time any resin will be damaged. If you rub your fingers along the surface and find a whitish chalking, that surface of resin has been damaged and is "dead". The glass it supports underneath is weakened, and what was once a rigid panel, is now flexible and weaker. All fiberglass roofs are vulnerable to this, and especially single skin layups will be most affected as a result. Fortunately any fiberglass product can be repaired and strengthened.

Many high end trailer manufacturers purchase much of their outer steel and aluminum sheeting panels, already prepainted before they are stamped. The white colour is more fade resistant than the darker ones, shows less wear and dirt, is more easily touched up if scratched, and less expensive to purchase. As you said, the lighter colours are also cooler as well.

Gard

      Hey Gard? Are you British?  I see you're using the Brit version of color ...  hee hee hee ... 

White, taupe, or silver trailers - but I've seen a couple of very nice looking black ones. The top edge matches the sides, but the very top of the roof will be painted white to reflect the sun.