That would be a good start.
I found that the tournaments in Warlock1 were a good place to meet new players, as I didn't know that many players at the time. That could be a good kickoff "promotional event" for the new subforum.
As for steam, I don't know the numbers but I suspect the steam forums can reach a greater audience. It's a real pity that the community is fragmented between the paradox and steam forums.