... take a look at this. I have been using this tweak since it came out but didn't see it mentioned here on the website after doing a search for it.
Change the Font Size of Web Pages in Safari for iOS with Bookmarklets
Although it may look like you can't see the whole bookmarklets script, just highlight and copy. It's all there.
This website has pics, additional explanation and tips that might be helpful, such as turning on the bookmarks bar feature in Safari.
Hope it helps someone.