White reflects more heat than silver, so many people (us included) have painted the top panel of their roofs white to help.
I did perform some tests in that regard, and it really does help. Several years ago, we were parked next to a 1971 Globetrotter (21') with our mostly white Argosy 20 (20'), and the interior temp of our trailer was significantly lower than our neighbor's. Currently, our 31' Sovereign
has a white painted roof, and a 13,500 btu a/c unit, and it stays as cool as our friends' 31' Sovereign
with silver roof and 15,000 btu a/c. Again, sitting next to each other.