Can we just create a meta: namespace on the wiki?
This is certainly an option. Keeping the discussion on the forums would allow other forum users to keep track of what is happening on the wiki at a glance even if they aren't active on the wiki, but then again it is relying on off-wiki organization too.
One of the problems with this particular wiki software is that it doesn't have all of the nice organizational tools that MediaWiki has, including dedicated discussion pages for each article. It also doesn't have separate genuine namespaces in terms of article searches and content separation, so it is also a mostly ad-hoc organization that would have to be made here.
I don't care what the organization might be, but we do need to get a decision down in terms of what system we are going to be using for this. It is also something that I don't feel comfortable simply making a decision on my own authority (which is none at all), and whatever we are going to be using may involve some "outside" assistance to get it going.