Is there a minimum distance I'd need to keep between the fans and belts/engine? I'm going to be swapping an aaz into my samurai in the next few weeks and I'm going to try and pull the rad back as far as possible to try and fit a fmic.
Not really. As long as you have plenty of airflow through your engine bay you should be fine.
like in a rabbit or golf, theres some space for rad/+rad fan air flow, and make sure wires and other stuff like water lines have space, tie off wires at places,, after so long they can come loose and/or 'rattle' around, can find the fan at one time or another.
Since it's an offroad vehicle, you'll need to think about how much the engine actually moves offroading (more than you think it will... maybe an inch). If you go were to down a steep hill in 4wd it could hit the radiator if its too close.