For me, it is also unreasonable to let oneself be eaten by mosquitoes. Just as it is unreasonable to have a locusts and wild honey diet, and wear camel hairs for garments (Wear something other than jeans and basketball shorts with t-shirts? Really? :D). And yet, Jesus did not criticize him for that and had him in very high regard.
However, I don’t think it is possible to truly be ascetic without being radical. Our reasonable minds cannot and will not understand the spiritual. For our minds it would be, like Kierkegaard would say, absurd. And yet, when we study the lives of spiritual saints - we find an incredible amount of absurdities. And still, their lives also show that they achieved their spiritual goals. It is a paradox, yes.
But going back to your OP. It is not a matter of a bare minimum but a matter of increasing one’s faith and avoiding it to be dead.