what about....
adding extensions to the existing poles. find the exact same size pipe for the extensions and insert a connecting dowel into the I.D. between existing and new. You might tack weld the dowel into one of the pipes to keep it stabilized within the joint, or just run in a short screw. With the pipes extended, you could use a small come-along hooked onto the existing hardware? one hook into the top of the pole and the other hook under the dock rail or the flange. Crank it up and re-set it, one pole a little at a time.