^
As far as i can remember, the Permalites do not want to alter their programming. Only Erek decided to go gung-ho, and regretted it soon after. Jake may get the crystal, but would be unable to use it.
They could have trapped the Chee into altering their programming, like how Jake convinced Erek to go along with his plans at the end.
And even if they force Erek. Erek would have the capability to pulverize Jake. And the Animorphs. And the Earth itself.
Change: Five Aux-Anis go with Rachel to kill Tom.
Effect: Rachel lives and Ax doesn't have to get assimilated! But the Auxes would might want to have revenge for the other Aux's mindless destruction.
minimalism:
3/10... way too direct. maybe have a fly cross the path of one of the auxes when they're secretly living in the hork bajir colony, making him swat at it violently enough that he falls down a hill and happens to overhear Jake's plan and gets the auxes to go with rachel in secret... though that one would probably fail for feasibility
feasibility:
6/10... I know that they've gotten out of really tight spots before so in the context of the story it's fair to say a group of them might've been able to take down the blade ship and survive it, but we all know in a story the very end is where you actually start to get a bit more realistic with danger, since it's the perfect time to finally let some main character be killed off... so I'm not sure, I'm thinking with a group of the auxiliaries, they might still have died trying.
satisfaction:
9.5/10... yeah, everyone wants to see Rachel live, or AT LEAST not have died in vain. but the lack of minimalism totally disqualifies your plan IMO.