I was part of the discussion group for NFSv4 spec the short comings of v2 and v3 have been fixed I'm a bit surprised by this. Which "discussion group"?
NFSD (v2/v3) is stateless other than the information provided by mountd (mount requests) and lockd (file locking). NFS is stateless save the state information remembered by statd. After all, that's the whole point of statd (and the NLM grace period).
A long time ago FileSystemHandle would stay the same between reboots and you wouldn't get this problem other than on an individual file. My XNFS says: 7.1.3 Stateless Servers and Idempotency [...] With a few exceptions, rebooting the server must not invalidate distributed state information. (with the exceptions being unstable writes, teporary files etc.)
To handle deleted files which are in use by NFS clients some servers rename them to .nfs* because if one client deleted and other clients where accessing the file then they would get Stale NFS handle. This rename takes place on the client on a REMOVE, not on the server. Cf. either McKusick et. al. or RFC 1813, 3.3.12, IMPLEMENTATION.
Once in a while a NFS server will do find $dir -type f -name .nfs\* -mtime +7 -mount -exec rm -f {} \; to clean up. Do you have any reference for that?
If you do not get the Stale File Handle error when the server reboots, it most likely means the FileSystemHandle is not changing between reboots I.e., it conforms to the specs.
but then you may have more security issues. Could you please elaborate on this "secutity issues"?