The nice thing about neoprene is it's resistance to ozone; which will breakdown regular rubber. And of course excellent resistance to petroleum products.
Walmart sells various thicknesses of yoga mats. There is a 3 mm thick black mat for around $9. Dimensions: 68? x 24? (172.7cm x 61cm). There thicker ones if needed. You can cut to fit.
Yoga mats are a good [inexpensive] solution but I am super cheap .......look for treadmills on the side of the road or on CL for free [does not have to be motorized but if it is also a free DC motor + controller if it rises a linear activator ] carry a ultility knife and cut off the treadmill Belt........strong large and free the scrappers will still take the metal etc.........good hunting