Great idea....I intend to use the same method next weekend.Ive found a secure and easy method to be 1/2 conduit saddles (size dependant on your rope light) from electrical supplies stores. Unscrew roofing screw and place on the saddle. You can paint them the same as your roof colour. Then come lights time, loosen slightly , slide in rope ligt and tighten down. Very secure, straight as a die and easy as.