I use a similar stateless password manager than the one where the submission originates from:
https://github.com/majewsky/pwgetMy tool uses a revocation list for scheduled password changes. Normally, the password is generated as
i = 0
return kdf(masterpassword, sitename, 0)
where kdf() is a suitable key-derivation function. However, when that password is on the revocation list, then i is incremented and the kdf() reexecuted until a non-revoked password is found.
The revocation list technically makes the password manager not-stateless, but I don't care. If I ever lose it, I can just generate passwords for each site and revoke them until I find the one that works.
For all the other concerns that you list, I have a textfile listing all my accounts, and the weird derivation rules that are required for some of them (e.g. "take first 19 chars, then append capital A"). That text file is in a private Git repo. Now you could hack my notebook to get at that repo, but if you do, all is lost anyway, so as far as my threat model goes, it's not a problem to have this text file.