Well to be clear, my fog enters the enclosure, and does NOT "stay" in there. If you have an all screen enclosure, it will all just escape going down/wherever it bounces. This is fine. This is how mine runs every night.
However, my humidity at night is excellent. Varies through the enclosure but whats important is where he's resting. That area is typically in the high 80s-100%. Most of the enclosure is similar. But my fogger is constantly running from 1am-6am. It's not like turning on, shutting off, fog sticks around, then turns back on.
It's constantly going, and I do not use a fan. I just have it go down the center of the enclosure (I'll try to get a video tonight), and it goes where it goes from there.
Do you have to use the PC fans? I feel like they'd be blowing the fog out prematurely. But without seeing it in action it's just a guess. Unless there's some reason you need them, I would try it without them.