Hi,
I wrote a document about how I am running NFS over stunnel. Using some firewall rules I was able to eliminate most of the complications for using secure NFS. It could probably use more detailed explanations, but the scripts I am using are all there.
It still kind of in test phase, but I am currently mounting my home directory using stunnel. I haven't really noticed much of a speed problem in day to day activities.
https://w3.physics.uiuc.edu/physwiki/doku.php?id=pcs:unix:nfs_over_stunnel
Please send any questions you might have.