I had something like a 100 fetish economy in a recent game as Lanka and it was pretty good, believe me
. Yes, it requires micro but why are you afraid of it. Outcome of a fetish is even bettee than outcome of a clam not only because of alchemizing fire gems to pearls but also because there're several very good endgame fire spells (Flames form the sky being the most obvious) that can really ruin the day of any attacker.
Also one of the biggest fetish-hoarding nations is Machaka who has even less problems with them as Black Sorcerers never die of disease and don't gather many other afflictions when diseased. Also nations with healing like MA T'ien Ch'i may equip cheap researchers with fetishes and set some Apothecaries to constantly heal. Your mages will almost never get feeblemind (mute does nothing for mages with one pick) and if you remove a fetish when mage has 2-3 hp he will most probably stay alive and may be equipped again. So you really don't have to even recruit additional commanders and pay extra upkeep - just use what you have!
I don't even mention nations who have commanders with native recuperation. These have almost no problems at all - just watch them and remove fetish in time.
Yes, it is micro. But it is extremely cheap gem factory as well.