I use your method after chasing off skunks, raccoons, etc. Now mine is suspended about 15 feet off the ground, directly in line with our windows
, between the house and a tree on nylon paracord. The cord rotates easily; even birds have a hard time perching on it. I have yet to see any mammal attempt it. I have two pulleys, one on the house and one about half way to the tree, kinda like the clotheslines spanning the streets you see in pictures of older dense cities. The platform feeder is attached to the moving loop, so I can reel it in for refills. Its very simple and after 4 years is still very effective in feeding only birds. We did have a family of flying squirrels last Summer and while I could never catch them eating the birdseed they certainly could and are so darn cute I wouldn't have minded. Too bad they are most active in the middle of the night.
The biggest problem was lubricating the far pulley. I ended up soaking a bit of sponge in oil, tying it to the cord with twist tie, and reeling it out where the oil was squeezed out as the sponge hit the pulley. It probably used way too much oil but it got the job done. I suppose I could have lowered the far end of the cord and dropped the pulley to the ground, but the sponge was far more fun. Still to learn if nylon cord reacts badly to oil. ;-)