If you clowns like nems, they might or each might take up their own.Awesome!!! Maybe the next one will take up residence in the front where I can actually see it... will my clowns host more than one neme?
For mixing BTAs, I have had success with my RBTA and my Black Widow living together. Their rock island seems to be a happy zone for them. They move, but only in a circle around the top of their rock island. This was by design to keep them away from the SPS island and the other parts of the tank--their rock is very knobby with lots of foot holds and right below the Noopsyche Mini.
Nem island on the left prior to getting wet, SPS island on the right
Some people report different BTAs fighting with each other or one type slowly withering away when another one is present. I run a lot of carbon for the nems and leathers in the tank, so maybe that helps, but you would want to monitor how they fare.
I have loads of RFAs in the tank as well, and they do their own thing far away from the BTAs. Mostly in the sand bed. I've wanted to try maxi mini nems as well but worried about a fish getting stuck in one. Would also love a sand bed LTA if I ever get a bigger tank with more sand bed space. A magnifica if I get a monster tank. Would LOVE a haddoni, but again worried about eating fish.