BTW, to those of you still following this thread, I had a very interesting conversation today with a quilter who is fairly new to our guild...
She said she and a friend bought a length of 100% wool carpet underlay pad for about $20 (US) with free shipping - they cut it in half and had more than enough to drape over the ironing board. She said it's a bit thinner than the "quilting" mats but comparable to the saddle liner pad I had with me. It measures 1/2".
I'm guessing it was a 6 foot width maybe?
Anyway - it's worth investigating if anyone is interested...and if you do, please update the thread on your findings.