Hi Lisa,

Yes, it does feel like you need a third hand, but i found that if i stand sort of behind the bike, lift it by the seat and reach down to pull back the derailleur with my right hand, it works. It took a little practice and still feels awkward, but not like it first did.
If you turn your bike over, you can mess up your bars, brakes, and/or shifters. Seat, too. Plus, to me, everything is then in a different place and I can't figure out what to do!

Robyn