Can’t recall if the bag is porous or not (meaning you can see light through it if held toward the sky or a light bulb) if so that shouldn't be a problem as long as you don’t mind a loss of audio quality. The Fives don't generate enough heat to be a problem.

You could wrap it in an old jumper and it’ll still work (for short periods anyway, before there’s a risk of overheating). 
 

The packaging is that - packaging. But it will offer some dust protection. Do you just wrap when needed? 

Get some speaker cloth and make yourself a cover, did that for my Subs and it is working fine.

I used this, many other colors and fabrics are available.

https://www.amazon.com/gp/product/B01HMBKNSS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1