Ive seen the outer/spider nicely cut down and the inner holes used to support a single ring,and with it being the inner its in arguably the best position.
Grind down all the outer teeth and you could cut away the metal not being used[the one i saw had that done]
Quite cool and practical looking
Basically as you know,the outer is the spider,it also has two sets of bolt holes on it.One for the middle[i got it wrong,sorry to confuse ]
and a granny ring[the little one/to clarify]
Ignore the granny holes and use the middle.Maybe best just grinding off the teeth rather than cutting it up.
I suggest a 'show us your SS m739 cranks' thread will show the crank i was on about.
Buggered if i can remember who was selling it or who bought it.I thought i a rather neat idea