I guess I have been doing it all wrong. The first batch of about 30 maroons that I raised (they are also at 4 months now) are in a 10 gallon tank that has lots of macros, a little live rock and even a BTA. There seemed to be a huge spike in violence right around the 2 month mark, but they have settled down and there are actually not even any shredded fins anymore. All of the little maroons used to be obsessed with getting to the anemone and were good and crowded around that general vicinity. IMO if they had been more spread out through the tank they would have picked on individual fish to a much greater extent. I am currently down to 5 of those original 30 ( people here in Des Moines loved the babies and bought them all up around 3 months old) in the 10 gallon and there is still considerable harmony. There is a lot of posturing, but no nipped fins and a relatively peaceful environment. There are 2 that have taken up residence in the BTA, 2 that have decided to host in a patch of macros, and one that is in the middle of the tank by himself wondering if he has bad breath or what.
For long term grow out of large batches of maroons I think that packing them into an aquarium at high densities keeps the agression spread out, but when faced with a smaller number of clowns, it has worked for me to give them a battlefield so that they naturally congregate in that area and one clown is not overly picked on.
How about some photos BCJM! I will try to remember to bring some into work tomorrow to share.
Best of luck!