Any reason why something like https://mods.factorio.com/mod/no_placement_restriction isn't sufficient for you?

I would say I wanted to challenge myself by making an altered version of factorissimo but the truth is I didn't know such a mod existed

That's fair enough. And FYI in future, any changes that you want to make to another mod like this, as long as the changes are in data-stage, you can do that with an add-on mod rather than a fork, which is generally better for everyone :)

You only need to fork if you are making significant data stage changes, or you want to change some control-stage scripts (and the mod doesn't provide the appropriate remote-interface API for it).