The small balls trick works ...
we had a topper installed on the 2012 Salem we owned and it worked extremely well but in the hot sun the material stretched.
stretched material would recover when it cooled down but if it rained teh weight would cause the material to sit on the roof top.
they protect against leaves, trwigs, some small sticks and the ever popular bird crap.
Remember the roof top for the slide out is what comes into your trailer - I for one do not like natures garbage inside my living space.
the new to us trailer has 2 slide outs without awning toppers but that is a job for next summer at this point.
2009 Heartland Sundance 31.5 XLT bunkhouse
2013 Ford F150 XTR ECOBOOST
"Of the troops - For the troops "