With regards to high UV applications, our current recommendation is HyperD 300. As a polyester, it is more UV resistant than nylon. It's strong, relatively lightweight (3.9 oz/yd²) and highly waterproof.
Please keep in mind that all synthetic materials will break down and fade with extended UV exposure. The damage caused by UV is cumulative, and due to the number of factors that play a part in UV exposure, we're unable to offer an estimated lifespan for any material.
Unless otherwise stated on the product page, RBTR is unable to offer any blanket guarantee for lifespan on any fabric due to UV exposure.