foam durability as it ages?

Yes,I'm a newbie to the board but long time builder of various projects... Done body repair all my life with lots of experience in many areas... My project it to build a teardrop with rear galley light enuf to pull behind my Harley and will sleep 2. Im tossing up between building an all aluminum, a glassed foamie or a hybred between the 2..... My intention is to put a somewhat pointed nose on a 4 1/2 x 9 and low ground clearance with skirts (and storage under bed floor) for aero. It will see many miles each year on all ranges of road conditions. Main question I have right now is durability with rough roads, vibration, and ageing plus effects of uv rays and weather... Has anyone on here had one with many miles on it and a few years of weather and sun? 
