Your appeal to evidence is a dead giveaway. It shows that you're still thinking in autonomous categories and defaulting back to an evidentialist framework.
In a Reformed covenantal framework, a presupposition is not a provisional axiom that can be reversed or tested symmetrically, but rather an ultimate, transcendental commitment—one that furnishes the very preconditions for intelligible thought and experience (i.e., what must already be true if reasoning, science, and evidence are to be meaningful at all). As such, presuppositions are not fungible hypotheses to be applied both ways, as it were, but principia that when consistently applied either ground or undermine rationality itself.
Asking such questions as "what evidence is there" signals a return to an evidentialist framework which assumes the very autonomy that presuppositionalism denies—a fallacious move. The issue is not the stock of evidences per se, but the epistemological conditions under which "evidence" has meaning.
There are no brute facts. Every evidential claim—including for or against evolution—is interpreted within a worldview framework. The question is not whether one can marshal credible or sufficient evidence, but whether the very concepts of "evidence" or even "design" can be intelligible apart from the triune God of scripture. They cannot. Only the Christian worldview provides the necessary preconditions: the Creator–creature distinction, the covenantal order of the cosmos, and the reliability of inductive inference grounded in divine providence.
Summary: The transcendental argument rests on the impossibility of the contrary: Without God, one cannot account for the rational structure of reality in which even scientific reasoning—like your critique—takes place.
