With access to the database creating a local export to be used as a directory of web pages on a local machine would be almost trivial. Then there is software to convert the same to be a PDF w/ index, or an EPUB or whatever other format.
As for just you or me, it would be trivial to abuse the web server and use wget or curl or similar to pull down complete copies of the forum(s) you are interested in. Depending on how the webserver is configured, there may be a copy already in the Wayback machine at archive.org
Whoops - just checked. There is a copy -
https://web.archive.org/web/*/forums.pelicanparts.com Pick a day, any day and see the madness. Didn't check the tech forums, but if OT and PARF are archived....
So amend that last one to " as long as the webserver config doesn't change regarding robots.txt and such, and as long as archive.org has funds for bandwidth and disk space..."
But yes, I can understand the desire to have a "offline" copy that you are in control of....
FWIW for a long time before the 356 Registry moved into modern times with a forum they used an email listserv. A true treasure trove of info. Since I had my own webserver at the time( 2000-2001) I simply set up mail, received copies of messages, archived and then processed them making a completely searchable indexed and fully linked archive of all the messages I had access to (multiple years worth). When gmail came out, I used my first invite (remember those?) to create a 356 related email address and only subscribed it to that list... I still have the account