Probably cheaper, simpler, and faster to use a deterrant like the below Fi-Shock pet and small animal unit to train the dogs to stay off of the couch. I've got one and it is not in-humane as I have "trained" myself a couple of times getting it set up. Tape some bare wires on the surface of the couch (or use aluminum foil pads/strips) and connect to the unit. The dog will get the appropriate immediate negative reinforcement when it jumps up on the couch and gets across the conductors. Pets are furry and somewhat insulated, so the contact usually needs to be with the feet/nose or other more exposed body parts. I think I got my unit at Lowes, but a number of places carry them.