I'll probably be sorry for mentioning this but I have three pairs in my 150. pair of false percs, pair of pink skunks and a pair of orange skunks.I also have three BTAs and a carpet. The oranges house the carpet the pinks house the larger GBTA, and the ocellaris house the medium size GBTA and BTA. I have had them all for a 1 1/2 years to 3 years I bought them all fairly small I dont ever have problems. But early on when i would add an nem it would cause a prob for a day or so until it was claimed Usally by the ones without a nem cause they were more persistant and didnt have another home to go back to. They are all doing great and so are the nems.
I would say if your putting them in your 150 you should be alright with one more pair. But as they said NOT maroons they are my favorite but also one of the meanest. I agree with the pink skunks or true percs both of which are nice and fairly tolerant. And as you said, add them to the opposite end. Add them nem first and shortly after add the clowns. You dont want to wait too long or the other clowns may try to host it and if you add the clowns first they may try to take the other nem over.
GOOD LUCK!!