I had not only those three dozen large plumeria stacked under the oak for the previous three weeks but also all my other larger, potted plumeria outside. The only plants I brought inside (10 days ago) were seedlings and newly rooted cuttings. Like you, we dipped into the lower 40's several times and touched 38 and 39 once. All those temperatures appeared to do was to kick those plants into dormant-mode. Everything has now been moved inside, since we had three mornings of freezing weather. Most of the leaves are still on all those plants (except those that were bagged).