Drue

Use the back side for sure. If you need a line or two for lining up your fabric, use a ruler and a permanent marker to mark what lines you need.
I also gave a used mat (craft table size) to DH for his shop and he loves it. He covered a table top with is and now can use his cutters to cut items with and not scar up the wood top. I have also cut used mats into some smaller sizes to have a mat next to my machine and to travel with...I just used the areas that were not Sooooo scored by the rotary cutters. You have lots of options.
My neighbor used one for his fish cleaning table...LOL,LOL