> 
> Has the Internet Archive, https://archive.org/ take a copy of the
> sites?
>

In the same spirit as this, have you considered some non-traditional and less
essoteric methods? For instance, start a window or screen recording of a VM
that is browing the site, and act as if the subject/user visiting the site.
Then, upload the video to youtube in a private link. Or, take the file and
PGP/GPG encrypt it, sign it and extract either a hash or a fingerprint and
send that to an email account held by a third party, say Gmail.

I believe that if you ever get into littigation against anyone, it would be
best to have your evidence held by a third party. And by evidence we must
include the timestamp, which seems to be a key piece of information. In both
cases I mentioned a third party holds that; in the former it is the youtube
upload date and in the latter the received date of the email held by gmail.
You can involve a fourth party, like a Yahoo account, if needed.

This can all be done with the help of an attorney acting as a leagal third
party, but it will not be as free as an email with the fingerprint.

I use the second method all the time for scanned hand-written documents and
other such items.