I did this last year and I'm planning on doing it again this year. I didn't have any problems with anything being ruined. What I did encounter was bugs making my seat a home, but I can live with that. What I did was move the seat into a position to where the back and bottom of the seat was exposed. That way when I got into it and flipped the seat into the correct position it would be dry. Only once after a couple of days of good hard rain did I have a problem. Luckily I thought about this before going out and packed an extra coat to sit on. I would highly recommend using not one but two ratchet straps. One on the top and one on the bottom.

The only reason that I did this was because I have two climbers. the one that I left hanging is much older and more importantly louder. So I had the option to keep my better climber for its intended use.