the normal rule can and should be followed with exodons. please try to understand this. your statement that the normal rules can not be followed is not only false but irresponsible.
the rule is 1 square inch per gal. so numbers cant even be a factor, as when you buy them from the lfs they will be all different sizes. also, they should be kept in a shoal of no less then 10 impo, so 5 to a 10g is wrong. also, 60 in a 120w would not be the minimum due to the footprint and size of the tank, so that theory is wrong again.
these guidelines are set for novice keepers, and others who may not understand things like aggression and bioload with these fish (or fish in general). sure, you COULD pack 30 of them into a 10g tank, but be prepared to pay for tons of food and 5x as much filtration as that 10g would normally need.
while they do well in an "overcrowded" tank, or "overstocked" by nrrmal standards, it doesn not mean that its a good idea to just grab a grip of them and stuff them into a tiny tank. there are many other factors that need to be accounted for, and not everyone understands all of that, hence the "rules".