I believe it's principally strategy 2, as well as more direct philosophical inquiries into the breadth of goals relevant here. For example, to some degree the concept of naturalness emerges in most people's image of a properly managed natural world, but naturalness is notoriously slippery and subjective, and the form of naturalness worth striving for is the sort of thing that could divide a room of competent animal ethicists.

Is it worth modifying the nervous systems of animals if this step can nearly eliminate their suffering, regardless of the lives we afford them? To what degree does the value of preserving a species diminish as we modify it from its natural state? Does conservation of species trump welfarism in any case (preserving screwworms for no positive ecological or welfare purpose)? Does population matter? Like, if we could maintain the genetic diversity of a species at 10k individuals, does maintaining a population above that level become justified when the average wellbeing level of those animals surpasses some arbitrated value? Is minimized or maximized population always better when other factors remain the same (species viability, average wellbeing)?

Is a species' reliance upon humans for survival a bad thing? Is there value in a self-maintaining ecological system as compared to one that is intensively managed? What amount of wellbeing or extinction-risk protection should be lost to gain some amount of self-maintainedness? This is basically just an elaboration of a few of the questions that arise only from the factors of naturalness, preservation, and welfarism. The necessary questions to be asked are emergent with additional factors of value. It turns into a messy field of ontological lines and consequentialist gradients as you add more.

Should we limit ourselves to management practices that operate through sterilization rather than killing? When does human activity supersede the interests of animals? What disarray could even this muddled bunch of questions be reduced to if an effort was made to parse the preferences and considerations of animals themselves, and co-balance all of these, rather than just apply anthropocentric priorities to them?  There could be some level of conceptual self-awareness in some animals, and their sense of what matters about themselves could be alien to our own.

When you wrote The Life You Can Save, how did you determine your recommendations for the percent of income to donate to charity? I have personally found it very difficult to determine how much I should give up for others, but believe almost all above the poverty line in the west can give tremendously more than you recommend. For someone seeking to maximize their impact, but also optimize their own enjoyment of life, what advice could you give for how to strike a balance with giving. Should the line be drawn where one would be giving up something they hope the world can afford to all people? What is meaningful enough non-necessary use of $1 if its opportunity cost is a bit more than 4 days of someone else's life? This question gives me trouble when I buy anything not strictly necessary.

You have individually had a greater impact on my personal ethics and the way I live my life than anyone else. Thank you.

Bonus question if you have time: Is there any research that could answer the question as to whether the cost to save a life grows at greater than 5.5% per year after adjusting for inflation? I ask because the math suggests investing beats immediate donation if the cost to save a life does not grow at a greater rate than 5.5% per year on average.