Hello Workstheworld, and welcome to our group.
Nice modding job there, but I would stay away from fiberglass entirely. Especially with open fiberglass, which your appears to be.
Every time you open the lids on chamber, or firebox, a tiny bit is going to float out... up, down and probably, into your food.
I'm sure it controls the heat, but I don't like little floating threads of glass in my food. It's almost as easy to ingest fiberglass without knowing it, as it is to inhale asbestos without knowing it. Once it is inside of you, it can cause serious problems, immediate or down the road awhile later.
I'm not picking on you my friend. I'm just concerned for you, and your family. I would keep your shields in place, but replace the fiberglass with a different insulating material, that is NOT a free floating disaster, waiting to happen to a family member.
I know you wouldn't want to hear a doctor say, "yes, we have to operate. There are numerous tiny holes in their intestines. We can cut it out and reconnect, but were not sure which other organs those strands may have penetrated, We'll have to wait and see."
In light of that, the $30 to $100 for a different material, doesn't seem like so much, does it?
Please do not read this post as an attack on you personally. I'm just concerned, is all.