A presentist argument for the Principle of Sufficient Reason, well sort of

1. (Premise) If presentism is true, reality is present reality.
2. (Premise) All contingent facts about present reality have explanations in terms of how the world used to be.
3. So, all contingent facts about present reality have explanations. (By (2))
4. So, if presentism is true, all contingent facts have explanations. (By (1) and (3))

Premise (2) is the controversial one. But it might be accepted even by someone who thinks the world came into existence causelessly, since present reality would still have an explanation.

It is, of course, unclear that the presentist can deliver on (4), since it is not clear that the presentist really can explain things in terms of how the world used to be. That depends on how well the grounding and causality objections can be answered by the presentist.