Mesh Like Material on Underbelly ---- Questions

I think it is an important water barrier.
I had a tire blow and throw the thread. The blown thread did cut up some of the barrier you are describing.
I cleaned up the area and used Gorilla Tape to cover the tears. This was several years ago and still holding up.
I check the areas above the tires looking for any tears or holes that may need taping.
This has worked well for me!
Pat