Thanks! I didn’t know about linked offset either~ good share. That will come in handy. 
Other steps that might improve your workflow:
Once you’ve made the yellow offset, switch to showing just the stroke and no fill. You’ll be able to see the stray nodes more easily.
To add a ring, make a circle, and a smaller circle on top; object to path; then add the resulting ring on the outside of the offset outline, maybe a third way in, then, path> union. Make sure the ring is quite thick so it doesn’t break easily.
Fun with Inkscape!