I'm not sure if you're using the strict philosophical definition of rationalist or not (the "requiring evidence" phrasing makes me think not -- that would apply to empiricists, not that they're mutually exclusive though they were at odds in the past). If you are, I'd suggest that the body of early Buddhist work contains lines of thought that aren't dissimilar from Plato who was most definitely a rationalist.
If you're using the term in a more general sense, then social science provides evidence for the efficacy of various Buddhist practices (e.g. mindfulness). I know the state of affairs in the social sciences are suboptimal (e.g. the replication crisis) but it's the body of knowledge we have to work with now.
Religious faith is by definition believing in hypotheses without valid reason. That’s all I’m saying. If Buddhist mindfulness is effective then that’s great. But I’m talking about evaluating the truth of hypotheses using faith.
If you're using the term in a more general sense, then social science provides evidence for the efficacy of various Buddhist practices (e.g. mindfulness). I know the state of affairs in the social sciences are suboptimal (e.g. the replication crisis) but it's the body of knowledge we have to work with now.