I have yet to make/install my sail panels ...BUT when I do I will probably put some insulation behind them just for the heck of it.
is it absolutely needed....NO, will it make a huge difference in noise and temperature control,probably not.
But what the heck...why not lol.
I plan on putting the insulation that I used on my floor and on my ceiling....behind my sail panels,behind my door panels and under my package tray....just so I know its there I guess lol.