I'm wondering about bio-load vs sustainable bio-mas? And enough surface to handle a ammonia spike(dead fish,dead coal,over feed) or a cascading crash event? In twenty words or less, that's my attention span... JK
Not sure what the question is, but the amount of ammonia handling capacity is up to the individual user. So you want lots of flesh in your tank then you'll need a aerobic filter system in place for your nitrifiers e.g. wet dry filter.
However imo I don't believe that creating your system to be able to withstand the death of an animal will be the most healthy system. If you do then yes go with a very large wet dry filter