Bearing in mind that part of how I got into this mess was by backing up everything on my file server, and reinstalling Ubuntu Hardy with a different username, which seemed to royally confuse everything having to do with file permissions…
I get “Permission Denied” when trying to add to an existing directory through fuse, but some directories will allow me to add a new subdirectory, and copy my files therein.
Turns out by correcting some files that were incorrectly set to root ownership, it’s up and running again:
sudo chown -hR eric:eric *
This changes everything in the directory and subdirectories to user eric and group eric. And now SSHFS is back to working the way I want it.