There's no way anyone that hasn't already been in the "Bob's mod" train already will jump in. There's just no place to start.
A PhpBB forum is far from the ideal way to do this thing properly. It's a waste of everyone's time, especially Bob's. You, Bob, have mentioned it in your own words how hard and time consuming it is to keep the information up to date or just even introduce it. Not to mention good explanations with screenshots and so on.
Therefore, introducing... the open source community tools! GitHub for example. I suggest moving all development, discussion, issues, bugs, wiki, information etc. to GitHub.
There everything is easily automatized (Factorio, remember?
![Wink ;)](./images/smilies/icon_e_wink.gif)
Let some passionate followers help you out with short explanations and a couple screenshots. Releases (versioning) would be automatically generated by git and everything provided by GitHub (you don't need any extra file cloud support). It's all there, for free, for everyone (no need to create account to download or read anything).
Keep your subforum, where you'll only post direct download links (provided by GitHub) on new releases and whatnot.
Let's start by your most popular mod and see from there. Let's get cracking.
PS: Bob, do you make frequent backups of your subforum? Because if something ever happens, you're going to be in deep shit without that. Just go to GitHub, or BitBucket.