Courtney,
I had a post here somewhere but for the life of me I can't find it. I'll repost the photos and hopefully they will help you a little. I wasn't worried about smelling like exhaust but I was having trouble with the oil getting on my rear wheel and brakes. I use 1/2" copper street 45 degree fitting.(A street 45 is small on one end, see the comparison pic) I made a slice in the small end, similiar to the way your carburator mounts to the intake, and used a small adjustable hose clamp to tighten it to the muffler extension. My goal was to aim the exhaust away from the rear wheel but in your case it will be a way to add a copper tubing extension. If you have access to a tubing bender ( cheapo available at Acr Hardware, Home Depot Etc.) you'd be able to make very nice bends in 1/2" soft copper to make the pipe fit wherever you want it. When everything fits together to your satisfaction slice the pipe like I did the 45 degree fitting, or use a fitting if needed and solder them together. (Use 95/5 solder, higher temp than 50/50 and stronger) There isn't enough heat at the outlet of the muffler to effect the solder joint. Make a clamp to hold the rear of the pipe or use rubber coated steel hose clamp and you're done. Hope this helps.
Tom