Should a patient with crest and periodic mild elevations of anticardiolipin antibodies avoid supplemental estrogen/progesterone, or do these supplements have a vascular protective effect?

Good question: Not a lot of data to rely on in your case. Intuitievly we know bcp usage has been associated with blood clots especially in women who smoke. So if you already have anticardiolipin ab which in your case , may or may not be clinically significant, i would avoid it. We know from the cardio literature that the cardio protection from hormone supplement did not help and the risk outweighed any benefit.

Crest: Hormone replacement therapies are not recommended because of the side effects.