There are some great sources of rip stop type nylon. The key is use some noodle power. The orignal reason for ripstop nylon was PARACHUTES so go online and look for use parachutes, or find a skydiving fabric supply store. THEY DO EXSIST the benefit is they offer a fabric called ZERO P which means it is non-porous and offers more lift with less air (pressure) to pass trough the fabric. It is fairly expensive, but well worth it, this stuff takes a beating. Just be sure to not expose any nylon to the sun for extended periods it will break down in a hurry
They have F-111 fabric and tons of other nylons that are pored like you would see in a kite or parachute pants.