I started out accepting that I would probably not be able to visblock with complex geometry like that and it works fine ingame, my computer blows and I still get upwards of 200fps.
I know you're trying to help, but my problem doesn't lie with performance or optimization, but with arbitrary limits on how many brushes I can use.
If I ever get the brushcount down I'll be using occluders and hints as well as I can, but it's not like the map would slow to a crawl for anyone without such optimizations.