There was a model of strongminds on the EA forum (https://forum.effectivealtruism.org/posts/dkQemkyzQXSh3xvov/a-model-of-strongminds-oxford-prioritisation-project). Like you said though, it's nothing compared to the amount of suffering that could be reduced by focusing on factory-farmed animals, specifically advancing clean meat.
If you flip the Rachels-Temkin spectrum argument (philpapers.org/archive/NEBTGT.pdf), then some tradeoff between happiness and suffering is needed to keep transitive preferences, which is necessary to avoid weird conclusions like accepting suffering to avoid happiness. As long as you don't think theres some suffering threshold where 1 more util of suffering is infinitely worse than anything else, then this makes sense.
Also NU in general has a bad reputation in the philosophy community (more than classical utilitarianism I think) so it's better EAs don't endorse it.