Can we make a custom paper size in Adobe Acrobat that has no length limit? Similar to a fanfold print type?
I don't have Adobe Acrobat available, but Acrobat is basically a PostScript driven format and you can set the page size within a wide range of choices, but not quite "unlimited length". I'm using the free PDF995 PDF creator, which installs a printer driver as do many other PDF programs. Here's how I can set the printer properties to get a page 8.5 by up to 200 inches long.
This works fine as far as the "paper" size of the PDF file, but you still must deal with the software that generates the document. For example, Word only allows page sizes up to 22" long, so you get a 22" length of print on a 200" "paper" in your PDF. Depending on how your document is generated, you may be able to do better. Good luck!