Some forums require for the first 10 posts or so to be approved by a moderator.
I think this might be our best solution. It’s not too hostile to either new or old users. Now, of course, the downside to this is that a potential troller could just do their trolling after their first 10 posts and go rogue, though I think that may be too much effort to go through for a troll. The troll wants immediate entertainment reward for slight effort, and I think just having to go through this loophole may be too much effort. I like it.