Gil successfully throws a lasso around a protruding piece of rock at 30' on the cliff face. (Use Rope is Dex-based, so I guess your result was 17?)

You'll still have to make a DC 15 climb check at 30', but at least you can use pitons to better secure the rope and maybe some special knots so that Ep won't fall all the way down and take 3d6 damage if he fails. Once you've made the check, you can tie the rope around something on the ledge so that the rest of your group can climb up easily.