Dude, your worries about that little bit of barrel catching on something are silly. The extra barrel protruding wont be any more likely to hang up on something than the full slide and barrel would. It sure seems like a much simpler and cost-effective method of getting what you're looking for. Cutting down a full G20 ruins a frame. For a little over a $100 you can drop in an extended G29 barrel and be shooting before the sun goes down.
"You find it offensive? Well I find it funny. That's why I'm happier than you."