Go with the 100'. It should be plenty strong enough. Also, from reading the ad on 50', it says, " The LCP line also has 20ft. of liquid crystal polymer rope spliced to the drum end of the line. This high heat resistant rope wraps around the first layer of the drum and protects the rest of the winch rope from winch drum overheating." If you have to wrap 20' around the drum, then you are down to 30' of rope to pull with.